RFC compliance is not a problem, but still there are SP-specific requirements on how these RFCs are supported and what the SP expects from our side. Also important, what SP is going to send toward us :)

For example, the numbering plan. Calls to UK, for example, should not be 0044.*, but 44.* with phone-context=national. I've got this information via a phone conversation, and not in a written document.

Everything works now, I'm just wondering if it's a standard practice to deliver such a poor documentation.





From: Jean-Pierre Schwickerath <swinog@hilotec.net>
To: swinog@lists.swinog.ch
Cc: Stanislav Sinyagin <ssinyagin@yahoo.com>
Sent: Thursday, August 18, 2011 10:52 AM
Subject: Re: [swinog] SIP gateway service documentation

Hello Stan

> The SP puts forward a number of requirements, such as
> national/international context in To: field, then some special
> requirements for CallerID privacy, etc. The problem is, we can't get
> a document that describes the technical details of the interface, and
> SP refuses to create such a document. All we've got is a number of
> emails and some information from phone conversations.

SIP and its extensions are fairly well standardized. Have a look at
http://www.packetizer.com/ipmc/sip/standards.html for an overview of
those RFCs.
We all know the PBX manufacturers and their developers seldom fully
comply to the standards so they should give you a good starting point
on how it's supposed to be done. You will have to test each and every
case with your SP unless he can garantee you he has implemented it
fully standard compliant.

> Is it a common situation for such a service? Am I too naive with my
> expectations to receive a fully documented service? If it were a
> no-name lousy cheap service provider, I wouldn't ask :)

We never had any issues when connecting SIP trunks to a provider as
long as they were using RFC compliant SIP (IMHO the RFC compliance is a
major decision point when choosing the SP). And I second you on the
point that the SP should document its extensions to the protocol if
they are not standard compliant extensions.

Regards

Jean-Pierre

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