Minor and unrelated semantic quibble:

“SIP reinvite” is not synonymous with “media path handoff” or “not anchoring 
the RTP through my network”, though it’s often improperly used that way in the 
industry.

A re-INVITE is just an INVITE message inside of a SIP dialog, rather than 
outside of one (the latter sets up a new call). It can alter parameters of the 
dialog (call), including media attributes (like endpoints, codecs, etc), or 
something that is purely related to the state of the SIP dialog (e.g. remote 
Contact (“target”)). 

So, while it is indeed common to use a reinvite to hand off the media to 
external sources, i.e. “why don’t you two send RTP directly to each other 
now?”, that’s only a very small subset of what reinvites can do, and the two 
are not fungible at all.

This has been an update from protocol formalities pedantry, and you may now 
return to your regularly scheduled programming of using words in that normal 
way where everyone understands what you mean just fine… 

:-)

— Alex

> On Sep 27, 2021, at 8:32 AM, Mike Hammett <voice...@ics-il.net> wrote:
> 
> PNIs need backups. Unlike most data, voice cares about latency, so if your 
> Ashburn PNI fails, now you're routing via Dallas (for instance), which may be 
> an unacceptable increase in latency, jitter, packet loss, etc.
> 
> With SIP re-invite being fairly common, just because you have a PNI for your 
> signaling doesn't mean your RTP follows the same path.
> 
> NTT/Telia/Lumen/etc. won't peer with you over an IX because the traffic 
> volumes to qualify for peering are enormous and usually inappropriate for 
> IXes. Well, that and protectionism. Also, for them, the Internet *IS* the 
> product. For a voice provider, the product is the voice service, the Internet 
> is incidental. The primary concern of IP peering for voice providers is of 
> data integrity, not cost avoidance.
> 
> 
> 
> -----
> Mike Hammett
> Intelligent Computing Solutions
> http://www.ics-il.com
> 
> 
> 
> Midwest Internet Exchange
> http://www.midwest-ix.com
> 
> 
> 
> From: "Ross Tajvar" <r...@tajvar.io>
> To: "Mike Hammett" <voice...@ics-il.net>
> Cc: "Paul Timmins" <p...@timmins.net>, "VoiceOps" <voiceops@voiceops.org>
> Sent: Monday, September 27, 2021 1:38:32 AM
> Subject: Re: [VoiceOps] Bandwidth East Coast Issues
> 
> On Sun, Sep 26, 2021 at 5:24 PM Mike Hammett <voice...@ics-il.net> wrote:
> I have IXes in areas where Inteliquent and Peerless have POPs. They haven't 
> had any interest.
> 
> I don't understand.
> 
>  I understand. Serious customers will pay for a PNI. Industry partners (other 
> large telcos with whom they exchange a lot of traffic) will get a PNI because 
> it is more reliable/higher bandwidth/etc. An IX presence may help customers 
> who send voice traffic over the internet, but I suspect those customers make 
> up a small percentage of any given telco's revenue. So, there's no incentive. 
> Same reason NTT/Telia/Lumen/etc. won't peer with you over an IX. Why would 
> they, when they can sell you transit?
> 
> _______________________________________________
> VoiceOps mailing list
> VoiceOps@voiceops.org
> https://puck.nether.net/mailman/listinfo/voiceops

-- 
Alex Balashov | Principal | Evariste Systems LLC

Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free)
Web: http://www.evaristesys.com/, http://www.csrpswitch.com/

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