Q. In the below REGISTER Request, there’s a mistake. Can you figure out on which header it’s present?
REGISTER sip:registrar.example.net SIP/2.0
Via: SIP/2.0/UDP pc33.example.com;branch=z9hG4bK74bf9
Max-Forwards: 70
From: "Alice" <sip:alice@example.com>;tag=9fxced76
To: "Alice" <sip:alice@example.com>
Call-ID: 3848276298220188511@pc33.example.com
CSeq: 1 INVITE
Contact: <sip:alice@pc33.example.com>;expires=3600
Content-Length: 0
a) CSeq
b) Call-ID
c) Via
d) To
Check 🔎
Correct answer: Letter a.
CSeq
is incorrect in this REGISTER request because the method is INVITE
instead of REGISTER
.
Q. In the below REGISTER Request, there’s a mistake. Can you figure out on which header it’s present?
a) “CSeq”
→ Correct. The CSeq should match the request method (REGISTER), not INVITE.
b) “Call-ID”
→ Incorrect. The Call-ID value is valid and unique as expected.
c) “Via”
→ Incorrect. The Via header format is correct.
d) “To”
→ Incorrect. The To header format is fine for this REGISTER request.
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