Already got back to the office, and need to return the loaned 3G phone which I used overseas. Before I gave up this cool baby, I would have to cancel the calling forward to get my phone number back to my blackberry. Since I am not good at remembering all these codes, I put them in this post for the future reference. Please be noted the codes here only for Verizon wireless provider.
To forward phone number A to phone B, use *72 + phone number B:
On the phone currently using phone number A, dial “*721234567890” and send. Here, *72 is the special code, and 1234567890 is the new phone number which accepts the forwarded calls.
To cancel the call forwarding, dial *720
To cancel the forwarding, just dial “*720” on the original forwarded phone, and that is it.
On both of the above processes, please do not forget the * sign at the beginning. And normally you will hear a continued beep sound, that is OK your request still goes through if your provider allows you to do the call forwarding (meaning you paid this service).
[updated on 2/27/12: from the comments below, it seems that *73 works for someone to cancel the forwarding as well. You can try both and report here if they both work for you]
[updated on 9/7/12: I tried and it seems that *71 can initiate the forwarding as well. ]