Mobile phones

Smartphones may be able to place voice-over-IP calls using a wireless Internet hotspot (or, with the right software, any decent Internet connection) by installing a softphone application and signing up to a VoIP provider. This is an inexpensive way to talk, avoiding fees for roaming or international calls – unless your Internet connection is expensive. When calling someone who's also using an Internet phone or app connected to the same servers, using a free Wi-Fi hotspot, the calls may even be free.

Some mobile phone providers offer to use the internet, either a local Wi-Fi or their own mobile data, for any calls, where 4G or Wi-Fi is available. They might charge as for normal calls also for these. If they charge as for local calls (+ roaming data?), this may still be cheaper than the normal rate for roaming calls.

VoIP calls are independent of the local telephone networks, but are limited by the availability of Internet connectivity, and sometimes blocked at the Internet firewall. If your Internet connection is by mobile data, these VoIP calls can be anything from free to expensive, depending on your mobile phone provider. In addition to voice they may offer video, text chat and file transfer connections to compatible applications.

Internet voice providers tend to fall into three categories: Some are generic Voice-over-IP gateways which follow an Internet standard (SIP) and allow calls to regular phone lines from users of any application that follows the standard – often for as little as a penny or two per minute, with no minimums (many small independents fall into this category; in the US, Google Voice may be another option). Others are proprietary apps (such as WhatsApp, Viber, Line, Skype, Facebook Messenger or WeChat), foremost connecting users of the same service, with calls to other systems usually treated as calls to the switched telephone network. The apps are downloadable from the app store for your phone operating system, most often for free. The third group caters to non-travellers, offering their own desktop VoIP phone to connect to your regular internet connection.

Using your phone in places other than its home area is called roaming. if you intend roaming, you should do your homework before you travel. You need to understand the price and what is included. If you're roaming the cost may be no different to home (e.g. most EU-based subscriber roaming within the EU), you may be able to pay a fixed fee per day, or the cost can be thousands of dollars for only moderate usage – depending on your carrier, contract and destination. You can pay to make calls, to collect voicemail, and even if someone calls you and is diverted to voicemail. Background data can accrue costs from the second you turn your phone on.

Consider using text messaging (SMS) as a cheaper alternative to making per-minute phone calls. These text messages can be sent between phones, with up to 160 bytes per message (messages can nowadays be longer, but are still delivered and paid for in such chunks). While SMS messages can be more expensive when overseas (from US$0.30 to 1.00 each), they are cheaper than international calls and can be very useful for keeping costs down. Sometimes receiving them can be free. Moreover, those who send you an SMS using a carrier back home will be charged at local rates.

There are two things you have to check to ensure that roaming will work when you arrive:

1. Is your phone the correct type and can it communicate on the frequencies required by the foreign network?
2. Does your home carrier have roaming agreements with at least one carrier in the country you are visiting,
3. Are you on a plan permitted to roam to another country or have you purchased a bundle that allows you to do so?

While roaming on your existing carrier lets you bring your home number with you, your phone must support the standards and frequencies of a network at your destination with which your carrier has a roaming agreement.

There is no need to unlock the handset or replace the SIM card, but if you're on the wrong frequencies or carry a CDMA-only handset into a country whose providers only support GSM, you will have no signal. Your home carrier should be able to tell you what networks are supported on your handset and plan.

Your carrier must have an agreement with a carrier at your destination to allow you to roam. Check that an agreement is in place and what frequencies the roaming carrier uses against the capabilities of your phone.

• Official EU roaming information page – for EU related information (tariffs, hints). Although in most cases EU usage supposed is billed against a subscriber's allowance, some exceptions apply, especially for providers that offer mobile data for bargain basement rates. In addition, some providers may only open their "roam at home" scheme to those who have established "stable links" to the their home EU country.

Check that your plan allows international roaming. It may need to be enabled, which is much easier to accomplish before you leave home. Many pre-paid plans do not permit any form of international roaming, limit the networks that you can roam to or limit enabled services (such as SMS only).

Most phones default to a setting which automatically chooses a network for roaming. When in areas near the border of your home country or intended destination, it may be worthwhile to change the setting to manual, and to keep to your home network until you lose the signal. The farther away from the border, the weaker your home carrier's signal; depending on terrain you might lose the signal already before the border, and likely at latest 5 mi (8 km) beyond it – but you avoid your phone picking up an expensive network across the border when your domestic one still works or when you don't need to be connected.

The foreign signal may actually be stronger also without crossing the border, especially in mountainous terrain, where the domestic signal is unreliable, where the signal path to the foreign tower is directly across water, and in backcountry, where no domestic towers are near. Mobile users in border regions like Niagara Falls, Windsor–Detroit or the Thousand Islands often disable roaming from the phone's menus to avoid being randomly hit with roaming charges on mobile telephones which never left their home country.

There are an increasing number of localized nano networks (especially in Europe) that may, unbeknownst to you, "capture" your mobile if you have set it to "automatic" network selection. For example, if you are travelling on a Stena line ferry the few miles between Scotland and Northern Ireland, the strongest signal is likely to be their own network with roaming charges of more than €1.50/min for incoming calls rather than the €0.05/min that the call would be capped at if you were still using an EU network. Cinemas have now got in on the act and are abusing what was once a socially useful technical advancement to stop phones ringing during performances.

At sea or in the air, out of contact with normal carriers, a ship or jet's local network connected by satellite may truly be a service for those needing it, but the prices may be outrageous for those who could get by without – or when automatically switched to when land based networks are still in reach (even in the harbour or airport).

A SIM is a card which is inserted into an UMTS or GSM handset (in older phones often under the battery). It is necessary on GSM phones, where it provides the handset's identity as seen by the network. In CDMA handsets the functionality was integrated, but most now accept SIMs (or the R-UIM or CSIM variety). Local SIM cards are often a much cheaper alternative to roaming.

There are 2 major types of payment scheme: pre-paid contract (sometimes known as "pay as you go") vs subscription contract (paid on each consecutive month, post-paid).

While a local SIM is usually much cheaper for local calls than roaming, other considerations may apply for calls from or to abroad, such as to friends at home. You have four options, the fees of which may differ significantly:

1. having them call your normal number (you pay a roaming surcharge)
2. your calling them with your normal number (you pay for an outgoing international call, plus the roaming surcharge)
3. having them call your local number (they pay for an international call)
4. your calling them with your local number (you pay for an outgoing international call).

With a local SIM, the phone – unless locked to the original carrier – is treated like a domestic one, with a local telephone number. Some prepaid cards include a small amount of prepaid airtime (typically no more than half the face value of the card, sometimes even more than it). The value of the airtime of course depends on call and data fees, which may differ from those typical on non-prepaid subscriptions, or between companies.

Prepaid SIM cards may work without account setup, credit card numbers or bank accounts or they may require registration (to reduce use of phones by criminals), either at purchase time or before usage. If registration is needed, you may want to get the SIM working before you leave the shop, to let the clerk solve any problems. In a handful of countries, purchase of SIMs by non-residents is restricted.

To add credit to these SIM cards, buy "refill" (the common term in the US), "top up" (Singapore, the UK, Canada and New Zealand), "recharge" (Hong Kong and Australia), "reload" (Philippines) or "add value" cards or vouchers from news stands, telephone stores or convenience stores. ATM or online credit card top-ups may be possible with some providers; however doing so through their websites may require the user to have a domestic debit/credit card or bank account. In some countries, credit (prepaid or plan) may be transferred between users of the same network by sending an SMS to the provider.

In some large international airports, outside security, mobile phone shops will offer a prepaid SIM without leaving the airport. A few vendors offer SIM cards intended specifically for visitors.

As a prepaid product, the SIM card and the credits have limited lifespans. Unless periodically reloaded (usually with a code purchased from a local store or on a website with a local credit card) the SIM and the local telephone number will expire. As a general rule, lower top-up denominations tend to expire more quickly.

The card is packaged as a credit card-sized piece of plastic from which you can break out a smaller chip card in one of three sizes (mini SIM, micro SIM, nano SIM). The chip is the same, there's just less plastic frame around a SIM in the micro and nano size versions used by some phone models (the original SIM was credit-card sized). Some very old phones may require a mini SIM a little thicker than those including nano versions, check if relevant for you .

A local SIM means one more number that you need to inform important contacts about; if you intend to visit many countries it may be easier to obtain a service which can be call-forwarded cheaply (such as a Voice-over-IP provider), distribute that number to your contacts and forward its calls to your local mobile phone/SIM when you enter a new country.

While voice calls should work as soon as you install a subscribed SIM card and re-apply power to the handset, data may require various settings to be configured so that the handset can find the Internet gateway. Usually the set-up is automatic using configuration data on the SIM card, but sometimes it has to be done manually via setting provider-specific Access Point Name (APN) settings:

APN: rogers-core-appl1.apn

APN Type: Default

APN Protocol: IPv4/IPv6

APN Roaming Protocol: IPv4/IPv6

If you are buying a SIM card, it may be worthwhile purchasing from a telco outlet so your phone can be working before you leave. This will save any confusion with having to apply settings yourself. Otherwise you may have to check the providers website, which can be difficult if you don't have mobile data configured. A few providers may also supply a username and password for mobile data. Carrier technical support is usually limited to providing a list of settings and advising you to ask your handset manufacturer. While MMS might only be needed for a specific few applications (usually, sending photos by text message), if you leave out the access point name (APN) you have no mobile data. Handsets purchased from individual providers usually preload the settings for that provider, but if you bring your own unlocked handset, you need to add your local SIM provider to the connection list for data. There may also be a setting to point the mobile browser to the new connection on the list, instead of your home carrier's gateway.

If your handset gives one-button access to voicemail, there is a number (listed in the configuration menu) which is auto-dialled by that feature. This number usually is read from the local SIM, but it's best to verify. Any on-screen "message waiting" indicators will only work for the currently-installed SIM, even if messages are waiting on your home provider (original SIM) and local provider (local SIM). Some handsets also use memory space on the SIM to store phonebook entries or Wi-Fi passwords; swap SIM cards and you may need to copy or re-enter this data.

An international SIM card is a SIM card meant for roaming in several countries. They are generally more expensive and more cumbersome than local SIMs, but free you from the need to buy a new SIM in every new country, with unused airtime left on the old one. Thus they may be an interesting option if you are visiting several countries in a short time frame (EU is an exception, as there a SIM bought in one country often works in all of them).

The "international" cards usually allow free or cheap incoming calls in a significant number of countries and offer relatively cheap outgoing calls via an automatic callback service. This avoids multiple changes of numbers.

In general, there are many companies that just re-sell services from several big roaming providers. More than half of all international roaming SIM cards are based on just three platforms:

• an Estonian platform with TravelSim, AirBalticCard and others (based on Top Connect OÜ);
• a Jersey-based platform on JT Telecom with an "UK" number, that is in fact from Jersey;
• on the Naka platform based on this MVNE from Switzerland

There are many different reseller companies available, so shop around – the prices can differ quite drastically The cards sold at airports may not be the cheapest. A full list and comparison of such services can be found on a specialized Wikia.

eSIMs, or embedded SIMs, act like SIM cards, however instead of installing a physical SIM card, you install an app that configures your phone's hardware to manage the relevant mobile network connections. Increasing numbers of phones accept eSIMs in addition to physical SIMs. Notably, most iPhone models from the X series and newer support this technology. This allows you to operate multiple phone and data plans in your phone, which is great for travelers. It also means that you can actually purchase an eSIM before your trip, and activate it the moment you step off the plane. Even though you can buy them long in advance, the eSIM does not get used until you activate it. This also avoids the hassle of going to a SIM shop, buying a SIM, and worrying about losing your home SIM as it swims around your bag for the duration of your trip.

Airalo and Nomad are examples of companies that offer eSIMs for over 200 countries, usually giving the customer various options such as amount of included data and the length of time for which the eSIM will be active. Additionally, these companies offer regional packages, whereby you can buy a single eSIM which will give you network access throughout Europe, Asia, or other regions.

Downsides include that not all phones, particularly cheaper or older models, support eSIM technology. Some phones don't allow installing eSIMs from certain other carriers, even if unlocked. Do your research before purchasing. For the security conscious, the thought of having a remote-programmable chip in charge of your data connection may be unpalatable. However, there is a security advantage to eSIMs too: if your phone is stolen, the eSIM cannot be removed by the thief, which gives you a better chance of tracking and possibly retrieving your phone.

If you want to use your own phone, you have to check (see above) that the phone can be used at your destination, type and communication frequencies and that it is unlocked (or "carrier SIM-locked".)

In some countries, providers may be required to provide subscribers with the unlock code for devices they own after a certain time period, usually for a fee. For many (but not all) common handsets, an "unlock" code may be purchased more cheaply from a wide selection of Internet vendors (typically US$10–20); more rarely a handset must be taken to a specialized vendor to be unlocked.

In Canada, beginning Dec 2017, cellphone customers can ask their provider to unlock their phones free of charge, and all newly purchased mobile devices must be provided to customers unlocked.

Unlocking a phone (to allow access to competing mobile carriers) is not the same as "jailbreaking" (which allow access to non-Apple software downloads on Apple devices) or "rooting" (which provides a "run as administrator" option for Android programs). Some phones are easier to unlock than others. Older Nokia phones can be unlocked at home with a simple code, while Motorola or Sony phones require additional equipment and may require you to bring your phone to someone. Some (Japanese domestic market phones) may use a different SIM-based method that attaches to your SIM, allowing you to take it from phone to phone. Shop around: unlocking services are generally cheaper and more easily available in Europe and Asia than in North America.

An alternative is to buy an unlocked phone. In some countries — for example China — phones are never locked. Various web sites and some shops in Western countries sell unlocked phones, usually at somewhat higher prices than the "deals" you can get by signing a contract for a service and taking a locked phone. Travel-specific capabilities like "quad-band", "dual SIM" or travel chargers, intended to keep handsets working on multiple carriers in multiple countries, are more likely to be available on factory-unlocked handsets from third-party electronics vendors. An unlocked 3G (UMTS/WCDMA) dual-SIM quad-band Android handset with no carrier-specific branding may cost anywhere from US$150 to 500 from an online mail-order house, depending on brand name and capabilities.

By having your phone and SIM (or eSIM) before you go, you will have your phone number to give out to family, friends and co-workers. You will have a phone that is ready to use as soon as you land. Your handset will come with complete operating instructions in your language, with information on how to check the remaining prepaid credit balance, how to add additional credit, how to contact customer service, and how to make and receive international calls.

This of course requires that you can get a compatible phone and SIM at home. These are not necessarily sold in the local shops, and may in any case be more expensive than they would be at the destination. In some countries these can be relatively easy to find; for example Hong Kong has entire street markets dedicated to phones and SIMs of all types, for use both at home and abroad. Otherwise Amazon has a decent selection of "globally compatible" phones that support the most common 2G, 3G, and 4G frequencies used around the world, as well as ready-to-use local SIMs for some countries. Also eBay is a good place to look for these, once you've done your homework and know what you're looking for.

• Egypt will now let tourists buy SIMs, although the system to register foreigners is somewhat convoluted. It's recommended to do so at the airport on arrival instead of trying to look for shops in town for the smoothest experience.

GSM (from the handful of major North American carriers that offer it) operates most often on 850 MHz/1900 MHz. AT&T and all three Canadian majors (Bell/Telus, Rogers) use 850 MHz/1900 MHz for their 3G (UMTS/WCDMA) networks. These are not the standard frequencies on other continents. Additional frequencies are used by new entrants, regional carriers or high-speed mobile data services.

AT&T and T-Mobile (USA) are GSM. European handsets might roam onto these carriers (for a price, usually fairly steep) if they support local frequencies and the home carrier permits it. 3G (UMTS/WCDMA) is supported by more carriers than GSM, but frequency assignments vary widely. An unlocked quad-band GSM or UMTS handset should be able to take a local SIM at destination. AT&T shut down its 2G network in 2017 and will shut down 3G in February 2022. T-Mobile, which purchased Sprint in 2020 and has now folded the Sprint brand into its own (though the two networks will not be fully integrated until mid-2022), plans to shut down Sprint's 2G CDMA network in January 2022 and its own 2G GSM network by the end of 2022. Rogers in Canada has shut down its 1900 MHz 2G network as of June 7, 2021, and its 850MHz 2G network will follow at the end of 2021.

Mobile subscribers in the US and Canada must pay airtime for all calls, in or out. (This is not true in Caribbean nations.) Handsets are assigned local, geographic numbers; one may switch from wireline to wireless service and keep the same number. Calling to a mobile telephone therefore costs the same as calling to a landline. A prepaid SIM will not work until "activated" by phone or (with some providers) on-line, as the subscriber must choose a city (which need not be their place of residence) from which to obtain their local inbound number.

AT&T, Verizon, T-Mobile (in the US) and Bell/Telus (in Canada) operate national networks, so roaming is usually not an issue within the country. Taking a Canadian handset into the US can be an expensive ($1.50/minute) misadventure as, unlike the European Union, there is no legal limit to what providers can charge for roaming. Downloading large amounts of data abroad has cost some users hundreds of dollars or worse. In addition, Rogers does not have its own network in the northern province/territories of Canada, and relies on "extended" coverage provided by Bell/Telus or Ice Wireless, which is not available to users with prepaid Rogers SIMs (visitors), so plan ahead and get a Bell/Telus SIM or you'll have to buy a separate prepaid SIM from Ice Wireless while in northern Canada. Meanwhile, competition within the US market has led providers there to significantly reduce what they charge for roaming to Canada; for example, Verizon prepaid costs $2 extra per day of use in Canada, T-Mobile prepaid plans can roam in Canada for only $5 extra a month, and AT&T doesn't charge any additional fees on plans that cost $40 or more to use them in Canada, making them the better choice for visitors planning on going to both countries.

There are a few small regional carriers; due to increased competition they generally don't charge extra for domestic roaming outside their home region anymore, but prepaid top-up cards are likely not in stores outside their home coverage area.

North American providers are notorious for flooding the market with branded handsets which are SIM-locked to one carrier on both pre-paid and post-paid services. A common tactic is to advertise an inexpensive (or even "free") handset in large print, while the fine print obligates the subscriber to a credit application for an expensive post-paid mobile subscription which takes years to pay off. Prepaid handsets are widely available at a reasonable initial price, but in Canada will carry a higher per-minute rate and inflated prices for mobile data (a dime a megabyte on low-end Canadian prepaid handsets, or a monthly bundle with 1GB for $30, is not unusual). In the US, prepaid plans are generally cheaper than postpaid at the expense of lower network priority, resulting in slower data at peak times.

For travellers and infrequent users, prepaid is likely the only viable option. There is a confusing array of brand names; some are major carriers, some are "mobile virtual network operators" (which resell bandwidth on the network of a major carrier, at a lower price), some are merely one of the majors rebranded under another name to give the illusion of competition. Prepaid minutes from one brand won't work with the others, even if they're using the same underlying carrier.

Refills (in the US) or top-ups (in Canada) for prepaid cards are generally available at convenience stores, filling stations, big-box retailers, pharmacies and Canadian post offices. It is often possible to refill using a credit card online. Some store-brand virtual operators (such as Loblaws or Petro-Canada in Canada or Walmart Family Mobile in the US) sell through their own stores (selected locations) or online only. Long distance on basic low-end prepaid plans is expensive ($0.25/minute airtime + $0.25/minute for a domestic long-distance call is the norm on the low-end "local" or "provincial" prepaid plans in Canada, while Internet telephony would cost a penny or two for the same call); it may be cheaper to use data-only service in conjunction with a VoIP provider like TextNow (US/Canada) or Google Voice (US only). There are also extra-cost plans to extend the meagre data allotment on prepaid mobiles. Direct-dial overseas calls (or calls to former +1 809 points in the Caribbean) are expensive on prepaid plans and best avoided.

Billing for calls usually begins when the call is dialled, not when it's actually answered; providers also round call lengths up to the next full minute.

Directory assistance is available at 4-1-1 or +1-area code-555-1212 but is expensive; advertising-supported competitor 1-800-Free411 or websites like 411.ca, 411.info or canada411.com are cheaper alternatives. Automobile association members may obtain mobile roadside assistance by dialling *222 (*CAA or *AAA); some specific services like #TAXI (#8294) will hail the next available cab in much of Canada or the US for a cost of $1.25-$2.

In the US, few retailers sell used phones; independent phone shops which can unlock a phone are rare outside large-city immigrant communities. Factory-unlocked handsets, used handsets and codes to unlock existing handsets may be purchased online, or if one feels comfortable, on marketplace sites like Craigslist or Facebook Marketplace.

Prepaid GSM SIM cards can be found at not just the stores of US mobile phone providers, but also many major retailers like Target, WalMart, and Best Buy. T-mobile offers one ($10) at their own shops or online, AT&T offers a SIM-only prepaid package on their website and stores. Another option is buying the least expensive prepaid phone; if you intend to move the SIM card to your own unlocked handset, do not insert the SIM into the phone supplied as (on AT&T "GoPhone") that will lock the SIM into that phone.

Some online services will ship prepaid SIMs overseas or ship specialised "travel SIMs" to North American addresses, but typically overcharge badly (for example Telestial or Cellular Abroad).

• Some providers in China use TD-SCDMA (an incompatible alternative to W-CDMA on 3G UMTS handsets) or TD-LTE (as an alternative to LTE on 4G devices). TD-SCDMA is quite rare, but most devices will support TD-LTE as it has also been adopted in many countries outside China.
• For visitors in India, getting a SIM card requires copies of passport and a few photographs. The procedure itself is easy, but the wait time from completion to activation may not be the same day. A 6 GB 4G data with 3 month calling can be availed for INR 350 (~US$ 5)
• Japan and South Korea had no 2G GSM coverage, but adopted the UMTS standard for 3G, and most modern phones with 3G capability on the local frequencies should be able to roam there (South Korea has both 3G CDMA2000 and UMTS coverage).
• Japan will generally not allow sale of SIM cards to foreigners on visa waiver or short term visas unless it is data-only; in general, your options are roaming (with a compatible LTE or 3G phone), renting a phone, or using a data-only SIM. This can be done at the major airports (Narita, Kansai, probably others) or via delivery to your hotel or business. Expect to pay $1–2 (¥100-200) a day, plus fairly high per-call/per-minute rates. For data-only SIMs, prices vary wildly as some providers charge anywhere from less than ¥5,000 (~US$50) for unlimited data for 7-days to a total of more than ¥10,000 (~US$100) for a SIM and a mere 5 GB of data good for one month, so do some research on this before leaving for your trip. There are a couple of providers that can sell voice-capable SIMs to short-term visitors, but they charge dearly for the privilege, with Mobal charging ¥4,500 (~US$45) for just 7 GB data with an additional per-minute charge for outgoing calls and SMS.
• South Korea now sells prepaid SIMs to short-term visitors also, with voice as well as data. However, not all SIMs can be activated after business hours, so check the details of the product you're buying if you're arriving at night or on a weekend.
• Visitors to Singapore can buy a SIM card from currency exchange stalls, service centres of the TelCo providers or 7-11 convenience stores. However, they are required to give their passport at the point-of-sale for the service to be activated. A user is allowed to have a maximum 3 Singaporean SIM cards registered to his name at a time.
• In Thailand, all three of the major providers have stalls at the big gateway airports (Bangkok, Phuket) selling tourist plans, and these can be a good deal depending on your data usage. However, if you're the bargain-hunting type or planning on continuing to another country afterward, consider looking for a convenience store that sells non-tourist SIMs in the airport instead; non-tourist SIMs from the three big providers can roam in neighboring countries for as little as 99 baht (~US$3) for 2 GB, and 399 baht (~US$13) for 7 GB in much of the rest of Asia, and have access to a rotating selection of promotions separate from the tourist SIM lineup.
• Major UAE carrier Etisalat has stores in both Dubai Airport(Terminal 1) and Abu Dhabi Airport. Prepaid plans are economical, purchase requires a passport.
• Makeshift SIM card stalls are available after exiting customs in most Philippine airports. Globe and Smart SIM cards are the ones most commonly available there. The Philippines has required registration of all SIM cards since 27th December 2022. Travellers can do this online through the official websites of the telecom provider that their SIM is connected to. This is a requirement to activate their SIM card. They will need a copy of their passport, entry passport stamps, and details of their Philippine address. SIM cards of travellers on short-term visits will expire after 30 days but those who are allowed to stay beyond that may apply to extend the life of their SIM card upon upload of pertinent documents.

• 3G usually on 900/2100 MHz (Telstra is 850/2100) and 4G on 1800 MHz and 700MHz.
• Note that Australia has some "external territories" served by separate providers than Australia proper, where you'll need to buy a separate prepaid SIM, if the option is even available (some don't sell service to visitors).

See also: European Union#Connect

In the European Union calls, messages and data should initially come out of your plan's domestic allowances if you have an EU-based SIM card, but there are still a lot of important exceptions and caveats. Most importantly, roaming may not be enabled at all with some cards, and in some cases operators are allowed to charge a (moderate) roaming surcharge. Surcharges are also allowed if you use the card extensively in countries other than the one the SIM pertains to – more use abroad than domestic use during a 4-months period. See ec.europa.eu for some details on EU roaming.

The EU rules on roaming do not cover calling a foreign number from the SIM's home country. If you are visiting several countries or use the SIM to call home, or European friends, make sure those calls are covered or check the separate price list.

Registration of SIM cards in Germany is now compulsory before they can be used. If you want to register your SIM at the same time as you purchase it, you need to purchase the SIM directly at a store operated by a telco (click on these for T-mobile, O2, and Vodafone shops) or its appointed partners (click on these links for a list of Lebara's and Lycamobile's partners) and bring your passport with you as registration involves verification of your identity. Although the process may sound daunting, the user does not have to be a German resident to purchase a German SIM card. T-Mobile can be quite picky though about requiring proof of address, so it's recommended to go with O2 or Vodafone, or if one needs the coverage, a reseller like Lebara.

When purchasing a prepaid French SIM card, activation is required. The user will have to follow instructions that came with the French SIM card, which either instructs the user to log-on to the provider's website or contact a hotline. Certain SIMs for short-term visitors may be activated without identification, but will automatically de-activate after 30 days if no identification is provided.

Visitors to Italy are required to produce a passport when purchasing a SIM card in order to have the service activated. In some cases, a photocopy of the passport may be all that is sufficient - this is at the merchant/retailer's discretion. You can purchase prepaid SIM cards at foreign currency stalls and at stores of mobile phone providers. You may also be asked to provide an Italian tax ID, but an unofficial version, sufficient for purchasing a prepaid SIM, can be generated online.

You can purchase UK prepaid (known here as "pay as you go") SIM cards at vending machines right before baggage claim in Heathrow Airport. Supermarkets and off-licence stores also sell SIM cards and top-up vouchers. Specialist mobile phone providers such as Lebara, Vectone and Lycamobile offer good rates for frequent overseas calls. At special events and public festivals, representatives of mobile phone providers give SIM cards out for free but you need to top up the required credit. Providers such as GiffGaff only operate online but their SIM cards can occasionally be found at certain events. Note that with Brexit taking the UK out of the EU-wide "roam like home" arrangement, UK providers are no longer obligated to include EU roaming in their service plans. All major operators have so far stated that new roaming charges will not apply to pay as you go SIMs, but this can change at any time, so check again before you buy.

Given the dispute over whether the Crimean Peninsula belongs to Russia or Ukraine, and given Russia's de facto control over the peninsula, most mobile phones that do not have a Russian SIM card will not work on the peninsula.

Selfies have become a ubiquitous part of society. What's the point of doing anything if you can't post a picture of it on social media? It's as if it didn't happen. Because of this, people have an insatiable desire to take selfies and often will dispense with all common sense in the pursuit of doing so. This can mean putting oneself in harm's way due to standing in a dangerous place or near a dangerous animal. Think about it for a second before making a mistake you will regret.

Also, if you use a selfie stick, check if your destination allows them; theme parks, concerts, museums, and sports stadia have all banned them due to safety issues or disruptions to other attendees.