This is my case. I have a VOIP line, and Google Voice account.
I have configured that incoming calls on the VOIP line, get redirected through my Google Voice account to my cell after 3 rings (so when I am not home, I can still pick up calls).
Works great with friends that have provider "A".
When friends with provider "B" call me, the moment I pickup on my mobile phone that's ringing, the call get's disconnected.
Made several tests. Had a friend switch SIM cards from provider "A" to provider "B". Everytime SIM "A" is used, the call get's connected. SIM "B" the call get's disconnected.
I am not sure if there's a setting somewhere on the OBI that could be adjusted... perhaps some kinf of sensitivity ir timing needs to be increased, since I believe at the moment the call get's answered, and there's some kind of call handout, provider "B" seems to think the call has been dropped...
(if the call comes from provider "B" and I am at home -- no google voice redirecion -- calls work OK)
Thanks for any info.