[SIPForum-discussion] P-Asserted Identity handling by UAS

[Andrew Yu]

Appreciate for any input on this issue. Thanks!

Andrew Yu wrote:
> Dear Members,
>
> I'm experiencing strange behavior from an UAS on the way P-Asserted 
> Identity is being handled in call forwarding & transfer scenario.
>
> *Call forward Scenario*
>
> UAS receives INVITE from B2BUA proxy of the following format:
>
> Request-line: INVITE sip:12345678 at UAS.com
> To: sip:12345678 at UAS.com
> From: sip:87654321 at B2BUA.com
> P-Asserted-Identity: sip:12345678 at B2BUA.com
>
> UAS call forwards and sent the following invite to the gateway:
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:6512345678 at UAS.com
> From: sip:87654321 at UAS.com
> P-Asserted-Identity: sip:87654321 at UAS.com
>
> Why does the UAS replacing  the P-Asserted identity? I was expecting 
> the following UAS behavior to use the P-Asserted Identity when 
> performing Call forward:
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:6512345678 at UAS.com
> From: sip:12345678 at UAS.com
> P-Asserted-Identity: sip:12345678 at UAS.com
>
> Or,
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:6512345678 at UAS.com
> From: sip:87654321 at UAS.com
> P-Asserted-Identity: sip:12345678 at UAS.com
>
> *Call transfer Scenario*
>
> UAS receives INVITE from B2BUA proxy of the following format, follow 
> by resolving of UAC location and sent the call to UAC:
>
> Request-line: INVITE sip:12345678 at UAS.com
> To: sip:12345678 at UAS.com
> From: sip:87654321 at B2BUA.com
> P-Asserted-Identity: sip:12345678 at B2BUA.com
>
> UAS receives REFER from UAC of the following format:
>
> Request-line: REFER sip:UAS.com
> To: sip:12345678 at UAS.com
> From: sip:6587654321 at UAS.com
> Refer-to: sip:91234567 at UAS.com
> Refer-By: sip:6587654321 at UAS.com
>
> UAS process REFER request and sent INVITE for call transfer:
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:91234567 at gateway.com
> From: sip:87654321 at UAS.com
> P-Asserted-Identity: sip:87654321 at UAS.com
>
> Why does the UAS replacing the P-Asserted identity again? I was 
> expecting the following UAS behavior to use the P-Asserted Identity 
> when performing Call transfer as well...
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:91234567 at gateway.com
> From: sip:12345678 at UAS.com
> P-Asserted-Identity: sip:12345678 at UAS.com
>
> Or,
>
> Request-line: INVITE sip:91234567 at gateway.com
> To: sip:91234567 at gateway.com
> From: sip:87654321 at UAS.com
> P-Asserted-Identity: sip:12345678 at UAS.com
>
> Please advice how should UAS behave when P-Asserted Identity is 
> received, whether the received P-Asserted Identity should be used for 
> Call forward and transfer. Thank you.
>


-- 
Cheers,

Asiatel Singapore Pte Ltd
Andrew Yu

19 Jalan Kilang Barat
#06-01, Acetech Centre
Singapore 159361

Tel: +65 6271 8233
Fax: +65 6274 4266