I've never been able to get this to work (not on the old XMPP GV and not now). I have two cell phones. One is with AT&T, the other with a Sprint PCS MVNO (previously with PlatinumTel/PTel and STI Mobile, both deceased). Neither one will get SMS messages sent to my Google Voice number, despite clearly having its box checked under "Forward Messages To Linked Number." And, under Legacy Google Voice, they're both designated as Mobile numbers.
Is there something either obvious or subtle that I'm missing? Is there a charge for the relay, requiring the account have to be funded for this to work?
My GV setup is as follows: Incoming calls are forwarded to a "landline" number I've had forever (now with a voip carrier via my Obi202). There are a total of five "linked" numbers designated, including the two mobile numbers. And the messages are forwarded to one of the mobile numbers. Doesn't matter which one, the messages never arrive.
I've attempted contacting Google support, but never received a response. Any ideas?
The easiest solution probably is to load the GV app on each phone.