[VoiceOps] Voice peering

Alex Balashov abalashov at evaristesys.com
Tue Jan 5 12:17:27 EST 2021

 From my perspective as an implementor down in the weeds, ENUM is just a 
failure-prone moving part and a source of unnecessary complexity at this 
point. DNS is not a particularly good transport vehicle for data 
queries. As far as I can tell, the industry went in that direction at 
the time it did because it was the more performant option at the time, 
which is a commentary on the sad state of SIP stacks early on.

Most folks realised a long time ago that SIP redirects are a lot more 
flexible for data queries, and doesn't require a parallel infrastructure 
of unrelated DNS componentry whose operational support demands 
nonoverlapping technical competencies. ENUM as a routing query mechanism 
has fallen into considerable neglect in some of the major softswitch & 
SBC platforms, as far as I can tell. I distinctly remember severe 
performance issues with ENUM a few years ago on one of the most 
well-known SBC platforms (ahem); when the vendor was contacted about it, 
the response was kind of, "Why would someone still use that?"

But, of course, that doesn't mean the peering provider landscape has 
caught up.

-- Alex

On 1/5/21 8:57 AM, Ross Tajvar wrote:

> Based on this presentation [0] from Comcast, they are interconnecting 
> with their biggest voice peers via SIP rather than SS7. They appear to 
> use ENUM for route selection. I'm sure others are doing this too, though 
> I can't find anything public.
> I'm interested if anyone has more info on how this works. I'm guessing 
> participants maintain their own private ENUM servers and just trust each 
> other? As far as I know the only way to validate number ownership is via 
> an LNP dip, which would be expensive to do for every call.
> I would like to be able to consume a service like that, at least in an 
> outbound direction; as a small operator, I'm sure convincing large 
> carriers to trust my ENUM server would be very difficult. But having a 
> greater degree of interconnectedness (and mostly importantly avoiding 
> TDM) seems like a good thing.
> Does anyone have experience with this sort of thing?
> Thanks,
> Ross
> [0] https://silo.tips/download/voice-peering-interworking-sip-and-bgp 
> <https://silo.tips/download/voice-peering-interworking-sip-and-bgp>
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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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