Thanks for all the responses made.
OK, now I can see it is a NAT/FW issue. Then, my next question is how my SIP UA can listen to real ringback in case of early media case. If ISP sets its own policy of not-sending-rtp-before-receiving, how can they deliver its own real ringback packets to caller UA? Will it not support early media?
Best,
Lee, Sungwoo
------- Original Message -------
Sender : Franz Edler<[email protected]>
Date : 2009-12-28 18:12 (GMT+09:00)
Title : Re:[Sip-implementors] No rtp coming in even after offer/answer
Hi Lee,
this is the typical behaviour of "port restricted cone" NAT (se RFC 3489 §5) - and well known for those digging deeper into NAT/FW issues.
best regards
Franz
----- Original Message -----
From: "이성우"
Date: 28.12.2009 08:47
To: "SIPImplementors"
Dear
Have you ever experienced cases that you can not receive any rtp packets even after finishing offer/answer negotiation is done, and can receive packets only after sending out your first to the remote party? Provided there is no fault in SIP signaling perspective, in what circumstances could we possibly meet cases like this? Wouldn't be NAT configuration or SBC policy in SIP carrier side? If so, will there be any specific reasons for this?
happy holiday.
Lee, Sungwoo
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