No, you do not have to have the sim in the phone for the forwarding to work. You can also forward/unforward from anywhere there is GSM coverage. Not neccesarily the home country of the sim you are forward.
So like you mentioned, you can forward your US sim, take it out, and put your other sim in it and you are on your way. You can also put your US sim in your phone while in India, and then unforward/forward (as long as the sim registers on a network) as you choose.
Originally Posted by
Mr. Bean
I'm curious, so I'm resurrecting this old thread:
My question is, do I need to have the SIM in the phone for forwarding to go through? For example:
US SIM ==> VoIP # ==> India SIM
Does that mean I need two cell phones, or can I just use one phone, set up forwarding on my US SIM, then take that out and replace with the India SIM?