H.263 crashing asterisk

i have (2) Vizufon CIP-5500 registered to my asterisk @ home box.

my asterisk at home then does an IAX2 connection to a asterisk server with a PRI card.

When I dial out from the CIP-5500’s to the PRI, asterisk on the remote box will crash.

Turning off the H.263 results in a good phone call and the remote asterisk (with PRI) does not crash.

If i register to the Asterisk with PRI, i can call out no problem and make video calls between the phones. its when traversing IAX that asterisk with the PRI will crash…

please help: alohatone@gmail.com