[SR-Users] subst_hf to rewrite a contact header

Hi, I’m wondering how to use subst_hf() properly. I’m trying to debug a broken flow by manually rewriting the contact header from Contact: <sip:b73c6f29-0101-4802-afcd-efb63f1e6d8f@10.10.10.12:5090;transport=udp> to Contact: <sip:2018092417381900003@81.x.x.x> by using $var(ctct) = "<sip:2018092417381900003@81.x.x.x>"; subst_hf("Contact", “/\<.+\>/$var(ctct)\r\n/", "a”); but the result is Contact: <sip:2018092417381900003@81.x.x.x> sip:b73c6f29-0101-4802-afcd-efb63f1e6d8f@10.10.10.12:5090;transport=udp Testing the regex with an external tool appears to match all of the original header, so I’m wondering why subst_hf doesn’t appear to rewrite the entire header. Is there something I’m doing wrong? TIA, Ben