Yealink Forums

Just found a weirdness on the old Yealink T28P. If you add any kind of SIP header containing three consecutive commas, the phone seems to freeze and doesn't answer to SIP INVITE. Using asterisk dialects, Extension 104-DEVEL will not ring if called this way:

SIPAddHeader(Test: ,,,);
Dial(SIP/104-DEVEL);

It will ring if called this way:

SIPAddHeader(Test: ,a,a,);
Dial(SIP/104-DEVEL);

or if called this way:

SIPAddHeader(Test: ,,);
Dial(SIP/104-DEVEL);

Thank you for your share, it's srange, we don't test like this.
Why do you want to test like this?
Do you test the same message to other phones?
And the firmware of the phones?

I came to this problem while working with Asterisk... an Yealink was called together to other phones requiring a custom SIP Header that happened to be in some case made of just commas.

I tested other brands and they will ring even if the weird SIP header is included in the INVITE.

The Yealink phone is running latest firmware.

Firmware Version 2.73.0.50
Hardware Version 1.0.0.39