Cellular Service Questions and Answers

Cellular Service Information by Carrier

General GSM Information

Cellular Abroad Questions

GSM Phone Usage


Cellular Service Information by Carrier

General GSM Information

What is GSM?
GSM (Global System for Mobile Communications) is the world's predominant mobile phone standard, first adopted in Europe and then quickly spreading throughout Asia, Africa and the Pacific Rim (Australia, N. Zealand, etc.). GSM enables the same cell phone to work in London, Johannesburg, Beijing, Sydney and virtually anywhere else on the planet.

The United States however, did not initially standardize GSM as a part of its infrastructure, instead leaving the development of cellular service to competing wire carriers which created whatever standard they wished including CDMA and TDMA. During the last several years, many US carriers including AT&T and T-Mobile aggressively embraced the GSM standard here in the US and other carriers, such as Sprint and Verizon have GSM capable handsets for service outside of the country.

What is a SIM card?
The SIM (Subscriber Identity Module) card also known as a "smart chip" is basically the "brain" of the phone, providing cellular service as well as many other functions including call log, voice mail and SMS and GPRS (internet connection standards). SIM cards are the size of a credit card but they have a pop-out chip about the size of a postage stamp which fits into all modern GSM phones. Currently, there are 3 SIM card sizes - standard, micro and nano. The smart chip is embedded with circuitry and when inserted into a GSM mobile phone provides wireless phone service on a particular GSM network. SIM cards are usually available prepaid or on a contractual basis, however Cellular Abroad only offers the prepaid version which is the most popular because of the user's complete control over how much they spend. There are no hidden fees or surprise charges. To see what a SIM card looks like, click here for our visual guide.

I currently have a GSM Phone. Will it work overseas?
It is possible that your current US GSM cell phone will work overseas. However, in order to use a different carrier, your phone must be unlocked. That means that you cannot simply take out the current SIM cad and replace it with another one. However, some phones already come unlocked from the carrier and others are unlockable. You will need to check with your carrier to ensure that your cell phone is unlocked or that it can be unlocked. All GSM cell phones sold through Cellular Abroad are unlocked and ready to use on practically all GSM networks and with all SIM cards. At Cellular Abroad we believe in freedom of choice for our customers in order to provide the best possible price on airtime and network service. Most other plans force you to use one system with no control over airtime pricing nor the lowest rates available.

What is a locked cell phone?
A locked cell phone is one that has been altered in order to use only one particular cellular network. This is often referred to as a service provider lock or "SP lock" for short. All GSM network operators lock the GSM cell phones they sell or offer with their cellular services. This is the hidden cost of the otherwise "free" or heavily-discounted phone you might receive directly from a network operator by signing a service contract. The cost of providing you with a "free" or low cost phone is subsidized over time through more expensive phone rates when you make calls domestically or roaming overseas. In the end, you end up paying much more for your "free" phone and service than you would if you purchased a package through Cellular Abroad and had the rock-bottom prices available everywhere. An unlocked phone is therefore one where this software restriction has been removed.

How is the cellular coverage in other countries?
Generally speaking, cellular coverage overseas is excellent-much better than average coverage in the US and Canada. Cellular usage is more common overseas than it is in the US and the GSM standard is a higher quality than many of the technologies available domestically. One point to make, however, is that buildings in Europe are sometimes many hundreds of years old. Thus they have much thicker walls than relatively modern US architecture, so if you are indoors and away from a window, you may have difficulty getting reception.

What are PIN and PUK numbers?
Some prepaid SIM cards have a security mechanism in place that requires the subscriber to enter in a PIN (personal identification number) code every time the GSM cell phone is turned on. When a PIN code has been assigned it is important not to forget this code. If you enter the PIN code incorrectly into the phone 3 times in a row then your GSM cell phone will display a Blocked message on its LCD. When this occurs you will then be required to unblock your phone using the PUK code. If you enter the PUK phone incorrectly 10 times in a row you will block your SIM card indefinitely. All phones have a different set of procedures to unblock and you will need to consult your GSM cell phone manual when this occurs. We strongly suggest that if you have the PIN-check feature enabled on your SIM card, that you turn it off. Please consult your phone manual's index under the "security" or "lock" section if unsure how to disable PIN-check.

How do I install a SIM card?
SIM cards typically are credit-card sized cards with a smaller SIM chip almost completely floating within the card and attached on one edge of the chip by some perforated plastic. The chip is approximately the size of a standard postage stamp folded in half. You can refer to this installation animation to get an idea of how easy it is to install a SIM chip into your GSM phone. Not all phones have similar installation procedures. For example, iPhones have a pin hold on the side of the phone and you will need to insert a SIM tray opener or a needle or similar object into the hole. The tray will slide open and in that tray, you will find the SIM card.

What is Bluetooth™?
Bluetooth is a wireless technology which provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a secure, low-cost, globally-available short range radio frequency. Bluetooth™ cell phones also allow you to use popular wireless hands-free earpieces and wireless speaker car kits.

Cellular Abroad Questions [back to top]

Is it better to buy or rent the phones from you?
There is no simple answer for this. If your rental period approaches 2 months, you would be better off buying the phone. Also, if you travel often, it makes sense not having to keep paying for shipping. Renting a phone is a good way to try out our phone and see if you like it. If you decide to keep the rental, you pay no rental fee. You simply forfeit the deposit on the phone. On the other hand, purchasing a phone ensures you will be acquiring an unused handset. In addition, if your cell phone is unlocked you can simply purchase a SIM card and use it in your current phone.

How can I be sure the technology won't become obsolete in the future?
This certainly won't occur in the near future. In fact, this is a relatively new technology in the US that many of the cellular service providers are quickly embracing. Sure, there will always be newer, smaller and "better" cell phones introduced in the future, but the underlying technology powering the service will remain the same. Consider classic cars as an analogy; while they may be less modern, they still get you around because even the oldest vehicles use gasoline for power.

How many minutes come with the SIM card?
The SIM cards usually come with call credits measured in monetary units such as euros rather than increments of time. This is because rate charges for calls vary depending on time of day, destination of the calls and other discounts or charges the carrier may apply. Also, with most GSM carriers providing free incoming calls to the user, the number of minutes on the SIM card could be substantial without the need to add more call credits.

If the SIM card costs $80, do I get $80 worth of talk time?
When you purchase the prepaid SIM card, you are buying the brain that inserts into your GSM cell phone and makes it work. There is always some credit included with new SIM cards, but the amounts vary from country to country. Additional airtime is purchased locally and usually available at or near face value. For example, a 25 Euro voucher will credit your SIM card 25 Euros. The remaining cost for the SIM card is a set-up fee which pays for service on this particular pre-paid account.

What are the calling rates and rental and purchase prices?
Rates vary from country to country and whether you are utilizing a country-specific or international SIM card. Please check the exact rates by visiting our Prices and Rates page and selecting the name(s) of your destination country(ies). Results will display per-minute calling rates, as well as handset and SIM card rental and purchase prices. Remember, with the exception of just a few countries, incoming calls (received within-country) are FREE - regardless of origin.

How do I calculate my rental period?
It is important to remember that your phone rental is measured from the date of your stated departure until your return date. If you receive your phone a week earlier, this will in no way effect the rental period. In addition, your rental period ends not when we receive the rental back but when you return from the trip.

I live in the LA area. Can I pickup a rental or make a purchase at your offices?
Cellular Abroad operates as an Internet business, not a retail location. Walk-in sales or will-call service is possible, but a $10 service fee will be charged for this service. If you're planning on stopping in, please call ahead for directions and availability of the item you seek. It's also extremely helpful to us-if you've already made your purchase decision prior to arriving-to supply your name, billing address and other pertinent information. This will help us to expedite your purchase. Our office hours are 8 AM to 5PM Pacific Time.

After my trip, could I use the phone I buy from Cellular Abroad at home?
The answer to this question depends on what network you currently use and if you're planning on replacing an old phone or looking to establish a new phone plan. All of our package phones will work only on GSM networks. (The phones cannot work on Sprint, Verizon or Nextel networks.) A lot of our customers find that a pay as you go SIM card is a great solution for infrequent phone users or as a starter or emergency phone for children or, if you have family or friends from out of the country coming to visit you, you can lend them the phone and have them pick up a prepaid SIM card from Cellular Abroad or from a cell phone store.

GSM Phone Usage [back to top]

Will my phone come with a charger?
Yes! All of our cell phones (for rent or for sale) come with a variable-voltage travel charger plus wall-plug adapters for overseas. Our rental phones are shipped pre-charged and ready to go with the SIM card already inserted. Our phone sales also come with pre inserted SIM cards but they do not come charged.

What is my new cell phone number?
Your new cell phone number is a local number for the country pertaining to your SIM card. For example, if you have an Italian SIM card, your number will be a local Italian cell phone number. You can also get a US phone number in addition to the local number. The National Geographic SIM card on the other hand already comes preassigned with a US phone number as well as a UK number.

Can somebody else use my SIM card?
Anyone can use your card. If you lose your phone with the SIM card inside, you can usually call customer service to deactivate the card so that nobody can use the remaining credit, though they won't be able to issue you a new card. You can also safely lend your phone and SIM card to friends without worrying about incurring any out-of-pocket costs. If they need more talk time, they can simply add some by purchasing a recharge card and using it with your SIM card.

Can I retain my US cellular phone number?
Yes you can. The National Geographic SIM card already comes with a US phone number and if you get, say a China SIM card, you can order a US number. Simply forward your current number to the new US number and you will receive all calls just like you would if you were roaming with your carrier. The main difference is that you also have a local number and the rates will be significantly more affordable.

Will I have voicemail?
Almost all of our services have voicemail.

What about email and internet?
Almost all of our SIM cards have data capability. We also offer data only SIM cards as well as hotspot rentals.

Can I use multiple SIM cards with my phone?
Some of our cell phones are dual SIM phones, meaning, you can insert two SIM cards into the phone. This is convenient for people who want to have local SIM cards for different destinations but also for travelers who want to have separate numbers for separate people, ex. One number for family and another for business.

If I run out of call credit, do I buy another SIM card?
NO! Remember, the SIM card is the "brains" of your phone and is rechargeable. Once you have a SIM card all you need to do is add credit for more talk time. Make sure that you do not wait beyond the service life of your SIM card to add more call credit.

How do I add more "talk time" to my SIM card?
In prepaid phone lingo, adding more talk time is known as "recharging" or "topping-up" a SIM card. Cellular Abroad sells recharge vouchers and we can add the credit on your behalf. The National Geographic SIM card also offers an auto top up feature where credit will be added automatically once it reaches a certain threshold

How do I roam with my country-specific SIM card?
First of all, Cellular Abroad does not support roaming out-of-country with country-specific SIM cards. (There are too many possibilities and variables for us to do this adequately.) That said, here are some rules-of-thumb for you to use if you plan to roam:

  1. Call customer service for your SIM card carrier to request or confirm that your SIM has roaming capabilities enabled. Roaming with some SIM cards may NOT be possible at all.
  2. Make sure to ask customer service if there are any variations in dialing to or from your number when roaming. (Perhaps the use of a different country code or dialing prefix, etc.)
  3. Ask customer service to provide dialing rates for making and receiving calls when roaming for all scenarios of interest. (Customer service may not be available from the U.S.)
  4. Make sure you have a good guesstimate of how much time you'll use the phone when roaming.
  5. Buy and apply adequate call credits (via recharge vouchers) for use when roaming. You may want to purchase a "backup" recharge voucher to use in case your SIM card runs out of call credits when you are roaming.

How do I know how much call credit I have remaining?
You can always check your remaining call credit. The instructions vary from country to country and are always provided with the SIM cards you purchase through us. They can also be found at the bottom of the Customer Service page. Typically you either call a special number or send an SMS message and the carrier answers back with your remaining credit.

What's the "Service Life" of a SIM card?
Prepaid calling plans provide users with the easiest commitment-free way to obtain a cellular phone number. For obvious reasons, service providers only have a limited quantity of phone numbers to distribute and it only makes sense to disable an account which has remained dormant for a reasonable amount of time. Most carriers refer to a service life as the time from activation (or recharge) of the prepaid account to a pre-designated cut-off time whereby there has been no additional recharge credit applied to the prepaid account. (Account activation usually takes place at the time of the first outgoing call.) Different carriers take different actions at the end of the service life. Most choose to decommission the SIM card, effectively disassociating the phone number from the SIM. Afterwards, the customer may be able to reactivate the account but will need to obtain a new number. Many services simply force the customer to obtain a new SIM card if the service life has lapsed. As long as regular recharge credits are being applied to the prepaid account (within the service life period), you should be able to keep the account active and retain the phone number associated with the account.

Troubleshooting [back to top]

I am currently overseas and I charged the phone and inserted the SIM card, but I still can't make any calls. What's wrong?
There can be many issues. Luckily, they are usually rectifiable. Here are some of the main ones. if your phone says "insert SIM," chances are your SIM card is not inserted correctly. If it says "enter subsidy" code then your phone is locked to the carrier. In this case, check with the phone's original carrier to see if you can get the unlock code. If not, you may need to purchase an unlocked phone. If you are picking up a network and still cannot make a call, make sure that you are dialing correctly. If you are and the call still doesn't go through, check your call credit. Regarding data connectivity, the main issue that customers have is that they have not set up the APN. This is an easy process to do. Please refer to the instructions that we provide with the SIM card. If you have purchased or rented a phone from Cellular Abroad, your APN is already set up.

What if my cell phone or SIM card doesn't work?
It is rare that one of our cell phones wouldn't work and extremely rare for a SIM card not to work. Almost all issues are user related issues and are resolvable...but you need to contact us in order for us to help you. We test all of our phones, including rentals and new phones, prior to sending them out to ensure quality service and no defects. While we do not test SIM cards, it is extremely rare that a SIM card is defective. Typically, if a SIM card doesn't work, it is related to the activation process or the credit has either expired or wasn't added in the first place. Please read and follow any instructions that we may provide with our products. Some countries require that we store information about our customers such as contact information within the country of travel. For any questions before or during your trip, please contact Cellular Abroad by phone at 00-1-310-862-7100 or email us at support@cellularabroad.com. Our office hours are daily from 8 AM to 4PM Pacific Time. We will be glad to return the call to save you money while troubleshooting your issue.

How do i know if my sim card is working?
If you purchased just a stand alone SIM card, the first thing you will want to do is to put the new SIM card into your phone to make sure that it is unlocked. If it says, "enter subsidy code" or "enter unlock code" or anything similar, it means your phone is locked. If it prompts you for a 4 digit PIN code, that is something different. Some SIM cards, depending on the carrier, come with a PIN code that needs to be put into the phone to use the SIM card every time the phone is turned on (you can disable this by going into the settings and then security in your phone). If it doesn't not prompt you for the subsidy code but starts to search for a network, that is a very good sign. It may or may not find one depending on the roaming agreements with the carrier. Our China SIMs and our Australia SIMs (and others) for example, do no roam in North America while others will. Even if it picks up a network, you should not make a call using the SIM card. If you really feel the necessity to continue testing the SIM, you may call it from another phone and the phone will ring. Do not answer it or let it go to voicemail. After the first ring, you should hang up. Please note that this is extensiveness is not necessary.

Will my phone work without a sim card?
Some aspects of your phone will work without a SIM card so therefore, it doesn't necessarily need a SIM card for some of the functionalities. The Wi Fi will work without a SIM card as it is not relying on a carrier's network. Having said that, sometimes you need to insert a SIM card in order to get the phone to do anything. This varies from handset to handset. In addition, some CDMA phones will work in some areas of the globe.

Someone else has my cell phone number? Why is that?
If you do not use your cell phone number, eventually, it will expire and will recirculate back into a carrier's numbering system. You may not know this but you don't "own" your SIM card number and therefore, the carrier can set the parameters on when they can take it back.

How does a sim card work in a cell phone?
The SIM card is the brain of the phone. It is what allows the service and to make and receive phone calls and use data. A GSM phone without a SIM card is basically a useless device (unless you use it strictly for Wi Fi).

Why is my sim card not working?
Your SIM card may not be working for a number of reasons. If it is a pay as you go SIM card, it may not have credit or be expired. Once it expires, usually there is a period where you can get the service back. Beyond that period, it becomes a piece of useless plastic. If, for some reason, you damaged the SIM card, for example, tried to convert it into a nano SIM and cut it incorrectly, it will not work. Another possibility is that the contacts are defective. Often times, users think that the SIM card doesn't work but in reality, either the phone doesn't work or the settings are wrong or the phone is in airplane mode.

Can I use my SIM card in another phone?
As long as the other cell phone is unlocked and the SIM card is the same size, you can make your SIM card work in another phone. If the new phone requires a smaller SIM card, you can cut it manually or with a cutting tool. If the SIM card is too small for the new phone, you can get a SM card adapter.

Does my phone have a sim card?
It probably does. If it is an AT&T or T-Mobile phone, it certainly does. Unless it is a an older Verizon or Sprint phone, it does as well. Newer phones, like the iphone 6, regardless of the carrier will always have a SIM card

How do calling cards work with cell phones?
You can use a calling card with a cell phone typically without a problem. Here is one approach; call the access phone number and then enter the access pin. However, most calling card numbers will automatically recognize your phone number when you dial their access number and thus, you will not have to enter a long pin code. In addition, there are many cell phone carriers that offer unlimited international calling straight from the cell phone without having to subscribe to another service.

Which are the phone carriers that use sim cards?
Most cell phone carriers worldwide use SIM cards but in the US, the most prevalent ones are T-Mobile and AT&T. Both of these carriers ONLY use GSM services which by default, uses SIM cards. Having said that, Verizon and Sprint phones, at least the newer ones, also have SIM cards but the SIM cards are just for the roaming services they provide.

How does a prepaid sim card work?
There are two basic types of services with prepaid SIM cards. The first is a monthly reoccurring service. For example, you pay $50 and the service will give you 30 days of calls, texts and data. Alternatively, you can put a certain amount of credit and it will deduct you depending on usage. This is actually called pay as you go as is more common outside of the US and Canada.

Should i get a new sim card for my new phone?
If you have upgraded your phone and it now requires a different size SIM card, you can and probably should get a new SIM card. If you are concerned that you will lose your contacts, you can have the carrier first transfer your contacts to your new phone. They can do this either on the cloud or by downloading it. Another way to do this is to simply cut down your SIM card. Still, new SIM cards typically have more memory than older SIMs and therefore it usually is a good idea to get a new SIM when you are getting a new phone.

Can i change sim card and keep the same number?
You typically can change a SIM card and keep the same number but, you will have to ask the carrier for a replacement SIM card. If you change from one carrier to another, say from T-Mobile to AT&T, you can port the phone number. Porting a number means that you can keep the same number with a different provider. This generally takes a couple of days to occur.

My phone is locked. How can I unlock my phone?
Sometimes the carrier will unlock your cell phone. It typically depends on if you are still locked into your contract or are month to month. Please read more about how to unlock your cell phone here.

What can you tell me about Cellular Abroad, Inc?
Cellular Abroad was founded in 2002 in an effort to provide international cellular service for the traveler. Back then, roaming was extremely limited and expensive. In 2006, Cellular Abroad became a licensee of National Geographic meaning that a portion of our products are branded National Geographic and adhere to strict guidelines as dictated by the collaborative efforts of Cellular Abroad and National Geographic. Since our inception, while our products and service has continued to evolve, our underlying philosophy has remained the same; to provide unparalleled products and service and to make them affordable enough for virtually any traveler who needs cellular service. Over 300,000 customers have benefited from our products since 2002.

Why should I buy or rent a cell phone or SIM card from Cellular Abroad?
As anyone who has spoken to one of our advisors, one of our main principles is to listen to our customers, understand their needs and then recommend solutions based on their individual needs. We do not upsell. On the contrary, we try to find the most cost effective solution for the customer. While this is atypical of commercial enterprises, this principle has created a loyal base of customers. In addition, we have products and services that you cannot find anywhere else. There are obviously many other reasons to rent a phone or buy a SIM card or cell phone from Cellular Abroad but these are certainly some of the more important reasons.

How do I get in contact with Cellular Abroad?
You can email us at info@cellularabroad.com or call us at 1.800.287.5072.

What is your return policy?
We have a liberal return policy. Please visit our Terms and Conditions page for complete information.

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