[Asterisk-Users] Polycom IP 600 not ringing

[Alex]

Hi guys,

Has anyone come across a problem when Polycom IP 600 does make an audible  
ring sound, even though the call comes in? I can see it on LCD and red  
light flashes. When I pickup the phone, everything is fine. It only  
applies to SIP calls. If the call comes in from PSTN via TDM400 card,  
everything seems to be ok.

The same scenario happens when I try to ring from IP600 other Polycom  
phones, again they don't ring.
I am using 2.6.1 bootrom and 1.4.1 SIP firmware.

Anyone can point me in the right direction?

Thanks,
Alex.