Miguel,
My impression is that RFC 3325 is intentionally vague about all this.
While two P-A-ID or P-P-ID headers are permitted, AFAIK there is no
explanation of what it means when two are present.
In the case of IMS, I believe it would be confused about which services
to apply if there was more than one P-A-ID, except in the case where
they denote the same profile. But it is the P-CSCF that inserts the
P-A-ID, and it has no idea what profile is associated with each ID. So I
imagine that the P-CSCF is going to just use the P-P-ID value(s) in some
way to pick a single P-A-ID value.
Paul
Torres Jose Miguel-MTORRES1 wrote:
Hi all,
I saw in one of the examples below that the UA includes two P-preferred-id
headers. I know that's Ok according to RFC3325:
"A P-Preferred-Identity header field value MUST consist of exactly one
name-addr or addr-spec. There may be one or two P-Preferred-Identity
values. If there is one value, it MUST be a sip, sips, or tel URI.
If there are two values, one value MUST be a sip or sips URI and the
other MUST be a tel URI. It is worth noting that proxies can (and
will) remove this header field."
I wonder what is the expected behaviour of the Proxy. I see two options:
1)if both are valid, the Proxy (P-CSCF in IMS) will choose one ramdonly.
2) the Proxy adds two P-Asserted-id headers, as per the two valid
P-preferred-id headers. Two P-asserted-id headers are also allowed according to
RFC3325
"A P-Asserted-Identity header field value MUST consist of exactly one
name-addr or addr-spec. There may be one or two P-Asserted-Identity
values. If there is one value, it MUST be a sip, sips, or tel URI.
If there are two values, one value MUST be a sip or sips URI and the
other MUST be a tel URI. It is worth noting that proxies can (and
will) add and remove this header field."
I didn't find in RFC3325 any sentence explaning the expected behaviour of the
Proxy when two valid P-preferred-id headers are present. Shouldn't that case be
considered in the RFC?
Miguel
----------------------------------------
Jose Miguel Torres
CND division - IMS System Engineering - Motorola
Tel: +34914002226, Mobile: +34629545668
INVITE sip:2300 at Asterix SIP/2.0
Via: SIP/2.0/UDP 192.168.1.126:5060;branch=z9hG4bK-276428-27856
From: "4302" <sip:4302 at Asterix>;tag=27642829233
To: <sip:2300 at Asterix>
Call-ID: 27642811596 at 192.168.1.126
CSeq: 20 INVITE
Contact: <sip:4302 at 192.168.1.126:5060>
Max-Forwards: 70
User-Agent: My UA
Privacy: none
P-Preferred-Identity: "4302" <sip:4302 at Asterix>
P-Preferred-Identity: <tel:4302>
Allow: INVITE, ACK, CANCEL, BYE, OPTIONS
Content-Type: application/sdp
Accept: application/sdp
Content-Length: 234
v=0
o=iS3000 0 0 IN IP4 192.168.1.216
s=-
c=IN IP4 192.168.1.216
t=0 0
m=audio 49368 RTP/AVP 0 8 18 96
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=rtpmap:96 telephone-event/8000
a=ptime:40
a=sendrecv
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