VOIP 求助: 原本工作正常，换了ATTUverse 的 2wire 3600hgv gateway 就听不见声音

I use sipura 1001 as VOIP adapter, everything was perfect. That time brandband was ATT ADSL.
The voip service provide is sigpate.

Yesterday, after changing brandband to ATT Uverse, then when making call and  receiving call, there is sound on my side.  The other end of the line can hear me, I couldn't hear anything.  
I tried to set port forwarding on the 2wire 3600HGV gateway, according to sigpate's suggestion:
port 5060 /UDP, port 5004 UDP and 3478 UDP  
I forward traffic on these port to  sipura 1001's box.

The problem still happens.

Any hint? Thanks in advance.