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REFER with no Implicit Subscription Example
REFER sip:carol@chicago.example.com SIP/2.0
Via: SIP/2.0/UDP client.atlanta.example.com;branch=z9hG4bKg45
Max-Forwards: 70
To: Carol
From: Alice ;tag=5534562
Call-ID: 849392fklgl43
CSeq: 476 REFER
Contact:
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
SUBSCRIBE, NOTIFY
Accept: application/sdp
Refer-To:
Supported: norefsub, gruu, …
Require: norefersub
Content-Length: 0
PPT Version