Yealink SIP-T4X Administrator's Manual page 426

Administrator's Guide for SIP-T4X IP Phones
5xx Response—Server Failure Responses
5xx Response
500 Internal Server Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
505 Version Not Supported
6xx Response—Global Responses
6xx Response
600 Busy Everywhere
603 Decline
604 Does Not Exist Anywhere
606 Not Acceptable
SDP Headers
v—Protocol version
o—Owner/creator and session
identifier
a—Media attribute
c—Connection information
m—Media name and transport
address
s—Session name
t—Active time
410
Supported
Yes
Yes
No
No
No
No
Supported
Yes
Yes
No
No
Supported
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Notes
Notes