Mitigating VoIP provider outages

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Dynamic

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#242606 5-Nov-2018 13:23

As I type this, the Voyager & Ufone VoIP outage is not yet fully resolved. We've had a quick chat internally about mitigating this sort of thing....

Where there is a DDoS attack (or another attack that overwhelms a VoIP system), presumably if you had a rule that forwarded calls to mobile phone if the on-prem VoIP PBX was unavailable, this forward would not actually work because the provider's VoIP systems were not in any sort of state to actually do the forward to mobile?

Likewise having a trunk with VoIP Provider A and a second trunk with VoIP Provider B..... if Provider A suffers a DDoS attack or similar, calls won't be forwarded to Provider B because Provider A's systems are not in a state to initiate that forward.

Perhaps it wouldn't be a terrible idea to have a hybrid solution with the client's main number being an analog/ISDN line with a converter into an on premises VoIP PABX, but all overflow lines and outgoing calling lines are VoIP. So if this kinda thing happens again, at least the client can still receive calls one at a time, and presumably request the analog/ISDN provider change the diversion from a forward-to-VoIP-line to a forward-to-mobile.

Thoughts?

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Beccara

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#2120228 5-Nov-2018 13:30

In the past my HA solution for inbound calls was an 0800 with one of the big 2 that used a DDI on each providers trunk as steppers. This way when Prov A goes down the number doesn't work and the stepper to Prov B kicks in.

Costly but it works. Other than that you could have a non-0800 with one of the big two with remote forwarding enabled where you could change the fwd'ed number but I don't think it'll preserve CID

Most problems are the result of previous solutions...

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hio77

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#2120246 5-Nov-2018 13:58

drop the voip, take up isdn again. problem solved right? ;)

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Dynamic

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#2120259 5-Nov-2018 14:29

hio77: drop the voip, take up isdn again. problem solved right? ;)

Absolutely! 'Progress' is not always a step in the more reliable direction.

Presumably its not that many years until copper starts coming out of the ground and we'll be in the same boat anyway.

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#2120265 5-Nov-2018 14:36

Depends on where you are, I've seen more copper issues (incl ISDN) than VOIP issues in quite a few locations. Running xDSL/UFB + 4g in an automatic failover solves most issues, 0800 and n+1 voip providers solved the rest. Conversely, I've also seen ISDN's (PRI not BRI) stay up for a few years at a time but those locations tend to be within a few hundred meters of exchanges

speed

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#2120272 5-Nov-2018 15:03

Dynamic:

<snip>

Where there is a DDoS attack (or another attack that overwhelms a VoIP system), presumably if you had a rule that forwarded calls to mobile phone if the on-prem VoIP PBX was unavailable, this forward would not actually work because the provider's VoIP systems were not in any sort of state to actually do the forward to mobile?

Likewise having a trunk with VoIP Provider A and a second trunk with VoIP Provider B..... if Provider A suffers a DDoS attack or similar, calls won't be forwarded to Provider B because Provider A's systems are not in a state to initiate that forward.

<snip>

Thoughts?

The first scenario depends on whether the forwarding is done at the provider's end or at the on-site PBX's end (because the attack is on the on-site PBX right?).

In your second scenario it is the provider being attached, so that will then depend on whether provider A is large enough to have their own SS7 interconnect(s) to the PSTN and enough control of their logic to enact the forwarding back out via their SS7 before the traffic hits the VoIP box that is being attacked.

It's a question of scale to have that sort of equipment though, so generally only the big players do it. Interestingly, a Voyager salesman told me just a few months ago that they have multiple redundant SS7 interconnect, so one has to wonder why they're unable to terminate and/or forward if they're being attacked on the VoIP side eh!

I was unaware of the outage as we ended up not going with them. Can you point to any other information about it?

Dynamic

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#2120306 5-Nov-2018 15:12

speed: I was unaware of the outage as we ended up not going with them. Can you point to any other information about it?

Cheers for the detailed response... interesting!

More information: https://www.geekzone.co.nz/forums.asp?forumid=42&topicid=242601

Note the link may not keep working as I believe the topic is in the wrong GZ forum... It's in the NZ Mobile forum not the VoIP one and if the moderators move the topic I think it breaks the link. The subject of the topic is "Voyager DDOS/ Voice Outage - 5/11"

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Quinny

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#2120307 5-Nov-2018 15:13

We are in Chch and with Exodesk who are via Voyager and affected by the above outage. Even they went down. Cannot praise them enough. Created a manual divert to my mobile for all incoming calls. Been a hassle yes but no biggie. Solved no phones with a call to mobile this morning (as both tech and senior staff at made sure we had their mobiles when moved to them). When outage longer than expected they sorted the above manually for us. Personal service is what you need and what we are getting.