Many have heard that they can switch out their phone's SIM card--the Subscriber Identity Module, or tiny smart card that identifies a phone and its subscriber--for a local one, but they weren't sure what this entailed. A phone that would work on foreign mobile networks and an impending trip to the U.K. made it an ideal time for me to give it a try.
Here's what I found:
Step 1: Getting the mysterious unlock code
Persuading your phone network carrier to give you the unlock code to your cell phone may be the most difficult part of the entire process.
The code is a number entered into U.S. phones to allow a SIM card from a third-party carrier to work with your cell phone. Internet message boards are full of complaints about carriers withholding codes along with offers of software or services for unlocking. But I also found a number of postings from people who said they got the code from their carrier simply by asking.
I called AT&T as a customer and explained my situation: I was going to the U.K. for one week, and would like to avoid high roaming fees by using a local SIM card. I explained that I had no wish to permanently change carriers, as I had a two-year contract and was happy with their service. Could I please have the unlock code for my phone?
I was met with a little reluctance. The first customer service representative told me this would require her to "submit a case" for getting the unlock code and that once approved it could take up to a week for the "unlock code team" to figure out the code for my particular phone. Her supervisor then tried to sell me an international plan that would reduce the usual $1.29 per-minute charge to "only" 99 cents per minute. I promptly declined. He then told me that it could take a week to get the code because it must be sent from the manufacturer.
I had already learned from AT&T's public relations team via another reporter that retrieving the unlock code merely involves looking up the manufacturer's corresponding unlock code for a particular phone's IMEI (serial number). They also said that the process should not take a week.
So, I politely persisted with my plea. After a total of 22 minutes on the phone, we agreed that AT&T would try its best to send the code in time for my trip and would call me the next day to update me on the status of my request.
About five hours later, AT&T sent the unlock code and instructions on how to use it to my personal e-mail account. (I took pains to keep a low profile, but AT&T may have easily figured out I was with CNET by simply Googling my name. I'm interested to hear from others who have made this request of their carrier.)
Step 2: Unlocking your phone, activating the SIM card
I chose Vodafone as my test case and went to its store in Paddington Station upon arriving in London. Gabriel, the Vodafone employee who helped me, was kind enough to let me verify that the unlock code and the Vodafone SIM card worked before he charged me for the SIM card.
Before doing anything, I confirmed my phone's IMEI by typing in "*#06#" and "send". AT&T had sent the unlock code for the correct IMEI.
Next, I removed my old SIM card, inserted the new prepaid Vodafone SIM card and turned on my phone. I was immediately prompted to enter my eight-digit unlock code and instructed to press "OK". Doing this made the SIM and my phone available for use.
Vodafone's activation process was simple. You activate, get your phone number, set up voice mail, check your balance and add to your balance by punching in a numeric code for each function and pressing send. The company gives you a little book and cheat sheet to remember the codes.
The SIM card kit, which costs $10 (5 pounds) and includes $2 worth of talk time and free weekend calls and texts, remains active as long as you use it at least once every nine months. This means you can reuse the same SIM card and phone number the next time you travel where that network is available.
There are several price plans to choose from, depending on variables like mobile TV, free nights and weekends, video or picture messaging, video calling, mobile broadband, unlimited monthly usage and texting. I went with the standard "Anytime" plan that was 60 cents for the first three minutes of the day and 20 cents after that. You could save more money by buying 70 texts for $10 and just texting.
I bought a 5-pound Vodafone "TopUp" voucher with cash and entered the 12-digit code it came with on my phone to add more money to the SIM card. The vouchers also are available via ATMs for the banks HSBC, Lloyds, TSB, Natwest or Royal Bank of Scotland. You can alternatively register your credit card with Vodafone and add minutes by texting.
Step 3: The road test. And: What about switching back?
The phone worked without a hitch. It was nice to be able to give people in the U.K. a local phone number for their convenience and also store their incoming numbers on my own phone. Also, phone numbers provided when calling information can be texted to your phone. That may not seem like much, but it can be much easier than struggling to scribble down a four-digit exchange and six-digit number dispatched by a fast-talking operator.
Upon returning home, I was a little nervous: Nobody from either AT&T or Vodafone told me how to switch back to my original service. Upon landing in New York, I simply removed the Vodafone SIM card, put my AT&T SIM card back in and powered on the phone. After a few minutes, my phone reconnected with the local network and I was back to my old service.
Things to consider
Your phone must be compatible with one of the networks used in the country you're visiting. My is compatible with GSM 850/900/1800/1900; EDGE; UMTS and HSDPA. The use GSM 900, GSM 1800 and 3G networks, so there was no problem.
Finally, there's no guarantee that your carrier or phone manufacturer will be cooperative in handing over the unlock code for your phone. A little extra patience while on the phone with the customer service representative and giving your carrier plenty of notice before your trip will likely help.
CNET News.com's Marguerite Reardon contributed to this report.