[SIPForum-discussion] Question about SUBSCRIBE method processing in proxy

[Yevgen Krapiva]

Hi.

Here is short description of incoming SUBSCRIBE request:

>SUBSCRIBE sip:user1 at kv-po-ykrapivanb.umc.com.ua SIP/2.0
>Via: SIP/2.0/UDP 172.20.177.70:18822;branch=z9hG4bK-d8754z->a53f3d4a240cb301-1---d8754z-;rport=18822;received=172.20.177.70
>Contact: <sip:user1 at 172.20.177.70:18822>
>To: "user1" <sip:user1 at kv-po-ykrapivanb.umc.com.ua>
>From: "user1" <sip:user1 at kv-po-ykrapivanb.umc.com.ua>;tag=801dfd1e

I've found that if proxy doesn't understand such or similar methods,
it will forward this request back to sender because of RequestURI.
Then the sender will send reply (Event Package Not Supported) to
proxy, and proxy again will forward response to sender.
So, the sender is appeared to talk itself.

Is this normal operation ?

Thanks.