[OpenSIPS-Users] Modifying INVITE header to add phone-context

[Julian Yap]

I have a PSTN gateway which requires a Phone-Context value in the
outgoing SIP INVITE message to further apply ISDN NPI/TON details.

Here's an example of what I currently have going out to the PSTN gateway:
INVITE sip:1234 at sip.server.com:5060;user=phone SIP/2.0.

This is what I require:
INVITE sip:1234 at sip.server.com:5060;phone-context=sip.server.com;user=phone
SIP/2.0.

Any clues on how to add the Phone-Context value?

Thanks,
Julian