Lost your SIM card?

Q: Do Sprint and Nextel share the same antenna reception?
--David

A: Though Sprint and Nextel are indeed one company now, they still operate two separate networks. Sprint runs on CDMA, which Verizon uses as well, while Nextel uses its own technology called iDEN. Since CDMA and IDEN are incompatible, you can't take a phone that works on CDMA and transfer it to iDEN or vice versa. So I'm sure you can understand that when the two companies announced they were merging back in 2005, most of the cell phone community was a bit surprised--it just didn't make a lot of sense.

That's said, the carrier has embarked on a plan to fold iDEN eventually into Sprint's growing EV-DO network. As part of that effort, Sprint released the Motorola ic502 last year, which is the first dual-mode iDEN/CDMA cell phone. It doesn't allow you to switch technologies at will; instead, it uses iDEN solely for push-to-talk calls and CDMA strictly for voice calls. While the phone is remarkable for that ability alone, we unfortunately weren't impressed with its limited features and low-grade resolution. If you're hoping to go the dual-mode handset route, I'd wait for something better.

Q: Can CDMA phones can be unlocked? And of so, can you take them from one carrier's network and use them on another?
--Steven

A: Though we always talk about GSM handsets when we use the term "unlocked phone," technically CDMA phones can be unlocked as well. It is possible to remove the settings that tie that phone to one carrier, but even if you're able to do so, it's a lot harder to then transfer the phone to another carrier's network.

Since CDMA phones don't use a SIM card, you can't just pop in a new SIM for instant activation with a new carrier. Instead, you'd have to go to the desired carrier and have them activate for you. While that's technically possible, unfortunately, I'd say your chances are pretty slim. The CDMA carriers such as Sprint and Verizon Wireless prefer that you buy a phone from them, so I can't see them being too excited about helping you circumvent that process.

Q: I recently cancelled a cellular account and removed the SIM card from my phone. Unfortunately, now I can't find the card. Are there any possible negative consequences from the card being used by another person?
--keithnewyork2

A: If you've canceled the account, the SIM card will be of no use to anyone else for making calls. If someone were to try using it in their phone, their carrier's network would recognize the card as invalid once the phone makes a connection to a tower. On the other hand, they would be able to access the card and find any stored phone numbers.