Proxy-Require
Firmware Version 1.0.3.6
uPNP, it can be set to "uPNP". The both parties will negotiate to use
which port to allow SIP through.
The default setting is "Keep-alive".
It is used to add the Proxy-Required header in the SIP message. It is
used to indicate proxy-sensitive features that must be supported by the
proxy. Do not configure this parameter unless this feature is supported
on the SIP server.
GXV3240 Administration Guide
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