delimeter

when adding uri-param, is there a way to change the delimiter used to separate the new attribute? Currently, am adding User-to-User in Refer-To header and can do that in HMR but the delimiter being added is ';' and our carrier says, I need to have '?'.

So this is what I currently send to the carrier in REFER:

Refer-To: <sip:+18889234033@globalipcom.com;User-to-User=abcdef12345abcdef>

This is what I need:

Refer-To: <sip:+18889234033@globalipcom.com?User-to-User=abcdef12345abcdef>