Grandstream GRP2613 Will Not Dial Out But Can Receive Calls

I just came across a rather unusual situation where I could not place calls but I can receive them. This was with a Grandstream GRP2613 (FW using as the VoIP provider. After examining packet traffic I found unexpected information in the SIP header and traced it to some settings under Account–>SIP Settings–>Custom SIP Headers. Specifically, I disabled “Use X-Grandstream-PBX Header” and “Use P-Access-Network-Info Header” which default to be enabled. Please see image below.

















Just wanted to share this in case anyone else runs into this problem.

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