Will the SIM from an AT&T phone work in a Verizon phone?

Episode 1146 (2:15:46)

Dianne from Williamsburg, PA

Dianne's 81 year old mother's cell phone was deactivated and she needs a new phone. Dianne wants to know if she could use the AT&T SIM in her old phone with an "Obama Phone" from Verizon on the Lifeline Assistance program. Leo doesn't think that would work. If not much time had passed, there's a chance that she could have her old number ported over to Verizon. But Dianne says it's been about a month since the old phone was cancelled, so that would be unlikely.

Dianne wants to know if she could have the phone numbers from the old phone transferred. Leo says that would definitely be possible, whether those numbers are on the SIM or on the actual phone itself. Leo recommends bringing it into Verizon, and they should be able to help her get her address book on the new phone.