Due to other tests, I had missed baresip account's ;outbound paramater. Once I added it, also reg-id was added.
-- Juha
WSS 192.168.43.160:50442 -> 192.168.43.160:5061 REGISTER sip:test.tutpro.com SIP/2.0 Via: SIP/2.0/WSS 127.0.0.1:9;branch=z9hG4bK5a4ad01f9164d358;rport Contact: sip:test-0x560871f65390@127.0.0.1:9;transport=wss;expires=30;+sip.instance="urn:uuid:9b21c1a8-dc58-a3d6-83d5-7be67cbe70ce";q=0.5;reg-id=1 Max-Forwards: 70 Route: sip:lohi.tutpro.com:5061;transport=wss;lr To: sip:test@test.tutpro.com From: "Test Account" sip:test@test.tutpro.com;tag=904f27750c59fc5b Call-ID: 69f4eea174d327eb CSeq: 29225 REGISTER User-Agent: baresip v1.1.0 (x86_64/linux) Supported: gruu, outbound, path Allow: INVITE,ACK,BYE,CANCEL,OPTIONS,NOTIFY,SUBSCRIBE,INFO,MESSAGE,REFER Content-Length: 0