Yealink SIP-T4X Administrator's Manual page 422

Administrator's Guide for SIP-T4X IP Phones
The following SIP request messages are supported:
Method
REGISTER
INVITE
ACK
CANCEL
BYE
OPTIONS
SUBSCRIBE
NOTIFY
REFER
PRACK
INFO
MESSAGE
UPDATE
PUBLISH
The following SIP request headers are supported:
Method
Accept
Alert-Info
Allow
Allow-Events
Authorization
406
Supported
Yes
Yealink SIP-T4X IP phones
support mid-call changes
such as putting a call on
Yes
hold as signaled by a new
INVITE that contains an
existing Call-ID.
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Supported
Yes
Yes
Yes
Yes
Yes
Notes
Notes