Yealink W60P Administrator's Manual page 485

What is the difference between enabling and disabling the RFC 2543
Hold feature?
Capturing packets after you enable the RFC 2543 Hold feature. SDP media direction attributes
(such as a=sendonly) per RFC 2543 is used in the INVITE message when placing a call on hold.
Capturing packets after you disable the RFC 2543 Hold feature. SDP media connection address
c=0.0.0.0 per RFC 3264 is used in the INVITE message when placing a call on hold.
For more information on RFC 2543 hold feature, refer to
information on capturing packets, refer to
Call Hold on page 243. For more
Capturing Packets on page 439.
Troubleshooting
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