Wife's iPhone can't connect to our VOIPO home number

[twodogs]

I've had VOIPO for a year and love it. The wife and I just switched our cell service to T-Mobile and got new phones. I have Android (Samsung Blaze) and she has an iPhone 4. The trouble is that my wife cannot connect to the home VOIPO number from her iPhone. When she calls, the home phone rings and I pick up. She can hear me, but I can't hear her. Her phone behaves this way for 20 seconds, then says "call ended". I also noticed that her iPhone continues to display "calling home" even after I've picked up. With a good connection, the iPhone should display the name of the contact ("home", in this case) with call duration underneath. That doesn't happen. So its as if the home phone has connected to the iPhone, but the iPhone hasn't connected to the home phone. Weird. I have no problems either way with my Android (edit - Android phone is having similar problems). The summary is:

iPhone to Voipo - Voipo seems to connect, iphone seems not to connect. iPhone hears the Voipo phone. Voipo phone cannot hear iPhone.
Voipo to iPhone - no problem at all
Android to Voipo - no problem (edit - Android hears Voipo phone. Voipo phone cannot hear Android)
Voipo to Android - no problem

Anyone seen this before?