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Hi,
>> I don't understand this "IETF SIP" versus
"3GPP SIP" thing.
>;>
>> "3GPP SIP" is a SIP profile, including
a number of SIP extensions, all
>> done in IETF. There is nothing which
a non-3GPP entity can't use.
>
>
>I said the
bifurcation exists _in_ _the_ _market_. Did you follow the
>link I
included? It's extraordinarily relevant. If you need more
>context: these
are screenshots from the SIP account configuration
>screens on the Nokia
E61:
>;
><http://www.nostrum.com/~adam/images/too-late.png>
I did follow the link. My question was not directly towards you.
It was a more generic question, because this IETF SIP versus 3GPP SIP thing
comes up quite often.
>We can argue over whether the split is real on
the technical level (and there are several reasons that it is -- for example,
using SigComp without proper signaling of the intention to do so ahead of time),
but it's all a moot point:
>products are already
being designed with two distinct modes of operation.
I think that SigComp
is a special case. SigComp is needed when you connect to IMS using certain
access technologies (I don't think SigComp is mandatory for all IMS access
technologies), so you need to study what the requirements are for those access
technologies. It's not necessarily something you negotiate in SIP - it's a
"pre-condition".
>>> What is "IETF SIP"?
What do I have to implement in order to be "IETF
>>> SIP" compliant?
RFC3261? RFC3261 plus each and every extension out
>>>
there?
>>
>RFC 3261 plus proper negotiation of any
extensions you choose to
>support. More emphatically: any behavior that is
not in 3261 or its
>references needs to be explicitly negotiated before it
is engaged. This
>applies to both clients and network
servers.
Just because you are able to negotiate it doesn't mean that you
are able to fulfill the requirements the operator has.
>Need something
more clear-cut? Something you can apply empirically?
>Here's a litmus test
for you: if the initial signaling between two
>network elements can't
negotiate down to base SIP without any
>extensions, then it's no longer
SIP.
If that is true, everything would work with 3261, and we
wouldn't need any extensions...
There ;are reasons we have defined extensions, and way to
require support of them, and that is because they are needed in certain
environements, and for certain services, features and use-cases. That is nothing 3GPP specific - anyone
designing/deploying a SIP based network and services may require certain
extensions in order to make things work.
Regards,
Christer
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