Client experiencing infrequent dropouts / disconnections on VoIP.ms. How to get near 100% reliability?

An issue like this is most often network related. Do you know the make / model of his network devices?

I have been using VoIP.ms with Cisco 50xG series phones for 5 years now - I don't think it's the hardware.

It might be the configuration - you also might experiment with using a different server for VoIP.ms, and/or check the bandwidth and loss rates between the client's site and the server he's using. Sometimes a server is physically closer, but more distant in terms of network distance, so changing the server the client uses might help.

Also, is the client's LAN healthy? Are the phones on their own LAN/VLAN, or are they sharing a network with bandwidth hogs? Is the overall bandwidth sufficient to handle however many simultaneous calls they're running? Does each phone have a dedicated connection to the switch, or are they running a cable to the phone, and then a cable to the PC from the phone such that the phone and the PC are effectively sharing a switch port?

There's a big gap in difficulty and resource expenditure between 99%, 99.9% and the classic 99.999% POTS reliability ideal. Respectively that's 3-4 days, eight hours, and five minutes of outage(s). A lot of residential ISPs only deliver effective 99% uptime because they will schedule a technician visit in a few days or next day if you're lucky. Business class often gets you same day help. Identify the points of failure and add redundancy. How much downtime can the client bear? 99.999% requires top quality equipment, redundancy at every level, UPS+generator, stockpiling spare parts, and automatic failover.

This is just basic troubleshooting. Try a different router, Internet connection, phone, and provider. It's easier to get redundancy for oubound calling than inbound.

How to get near 100% reliability?

Step 1: Get off the largely self supported service that has never promised 99% reliability. They sell "99% satisfaction rate" and best effort support.

Are you reselling Voip.MS or is this their own account?

Would you be able to test the phones on a different service to compare the results? It sounds like the service to me. I assume the phones are properly registered and that the server may be restarting them due to some bug.

This stuff is pretty much always related to the ISP/Internet at large.

Have him do some of the more common voip tests to see if there is a pattern in terms of packet loss, jitter, buffer bloat, etc. No single test (unless to the provider themselves) is definitive, so testing in aggregate is useful.

You can sometimes pick up a little bit of performance from picking specific models of modems and routers, but typically if a line is no good for VoIP, nothing short of a miracle will fix it.

FWIW Ringcentral has a nice VoIP diagnostic test. If you get a clean test to them, you could always switch over.

I would start at the router, this can be commonly caused by sip alg, or rtp timeaouts, aggressive natting etc.

If some of your customers are fine but others are not... its more than likely not the phones. Usually it's the route / peering it takes to get to your customers. Does VoIP.ms offer any kind of private peering or vpn tunnel for an extra fee?

Now if his voip phone resets in the middle of a call.. that's usually a hardware issue.

"Sometimes, when a customer is dialing the main business number and punches in his extension, the customer receives a message that "this extension does not exist"." That's a problem with the pbx platform as they should never hear that. Who ever your pbx provider is... this is something for them to troubleshoot.

Basic steps

Confirm phones on latest firmware, confirm edgerouter is on a Stabile build, confirm no bandwidth over utilization confirm your wan connection is stable ....I always start there because you need to rule it out before going crazy

try voip.ms's premium rate instead of the cheap rate

Or his VoIP phone resets in the middle of a call.

This whole post is the bane of tech support, but this part in particular caught my eye since you mention PoE and nobody has touched on it. This tells me either the phone is wonky (unlikely), but most likely the network cable/poe port is misbehaving. Move the phone to an AC adaptor and see if resets keep happening.

Generally ISP issues/routing/maxing out local network/QoS or router issues is the culprit in these cases but... phones dont reset unless something bad is happening locally, and it's probably a misconfigured network that works good enough for general stuff, but voip is very good at finding issues in local networks.

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