Yes
Any cell phone that is unlocked requires a SIM card to work. If you own a Sidekick cell phone that is unlocked you are able to use a carrier other than T-Mobile. For this reason, it will require a SIM card to work.
If the T-moblie Phone is locked no if unlocked yes. try it.
yes, if its unlocked. you can put an att or t mobile sim card in the sci phone and either will work. i think those two work unlocked or not
According to Zain mobile they do. It needs to be an unlocked GSM phone or a Zain phone that accepts a SIM card.
If it's an unlocked phone and supports the same frequencies as the carrier on your sim card. Then yes, it depends on the model of your phone.
If the handset has been unlocked from its original network, then yes.
Just like any other unlocked phone, a unlocked treo basically is not limited to a particular mobile carrier. For example, a phone locked by Sprint can only work on the Sprint network. If you put a SIM card from, say Verizon into the phone, it will theoretically not be able to make calls or send and receive messages. No such restriction is present on an unlocked phone.
You can - but - it will only work if the t-mobile phone has been unlocked !
If the phone is unlocked you should be able to put any type of sim card in there as long as it is a GSM phone with a sim card slot.
Only if the T-Mobile phone is unlocked. If the T-Mobile phone is still locked, only T-Mobile SIMs will work.
There should be no problem if you use a SIM card in an unlocked phone. If the phone is locked make sure the network is available to you.
If the phone is unlocked it can be.