Hi Seth,   You don't see this issue when you have only UC500( with NAT on UC500, no SA500) because UC500 NAT is translating both "c" headers from Internal IPs to external IPs. So it doesn't matter if the other end is RFC compliant or not as they woul...

Hi Seth,   As Maulik mentioned in the other post,  this issue is also caused by the SP side not being RFC3261 compliant as the RFC clearly states that the SIP end points must honor the 2nd c= line over the 1st c= line in the SDP (1st and 2nd are with...

Hi Seth,    I can see one thing in the logs that can be causing the problem if the SP is not using the correct "c" contact header to send the RTP. Currently UC500 is sending 2 contact headers.  Can you apply this on UC500 and try the call again with ...

Can you check under Network Configuration on the 525G phone if you have the correct TFTP server set-up.If you are using default IP addresses, try this - Under Network Configuration, Enable Alternate TFTP, manually enter 10.1.1.1 as TFTP server 1, sav...