[asterisk-users] Grandstream GXP2000 Loses Connectivity

[Peder @ NetworkOblivion]

I have 20-30 GXP2000's connected to * over a T1 line.  Neither end is 
NAT'd and there is plenty of bandwidth available over the line.  The 
GXP's are 1.1.5.15, which is the latest.  I have a problem where the 
phones keep dropping off of * and I get a "failed to register" message 
in the log of *.  Sometimes they eventually connect and sometimes, I 
have to reboot them to get them to reconnect (I never change the config 
though).  Has anybody seen this?  I've tried lowering the Register 
Expiration and that seems to make it worse.  If I lower it to 1 minute 
or 5 minutes, I lose them every 10-15 minutes.  If I put it at 10 
minutes, it loses connectivity once or twice a day.  I tried Grandstream 
support and their answer was completely useless.  Has anybody seen this? 
  Or does anybody have any ideas?  Again, no NAT involved, so don't say 
STUN or NAT issue.

Peder