Do you happen to know who you spoke to at t-mobile?
I ended up enabling pressing 1 to pickup the call, and this appears to have fixed the issue for me (even though this is a little bit annoying to have to do). My sip account picks it up first, and the cell phone call shows up as a missed call.
I don't know who I talked to. I had to call twice before I got it right. Unconditional Call Forwarding settings seems to be what he did, as in the above post.
I finally figured out how to write a script that toggles sip on/offline, and changes the enabled phones in google voice for me. So now I can click a button when I leave home, and click it again when I arrive back at home. I made a queenbeecon button with it.
Now I just need to automate this based on the network I am connected to.
I will try to post it here in the next few days when I have more time.
anyone knows how to play with the settings of the sip application?
i need to add a filed to send the caller id (symbian phones have a "public username field")