We have had wired broadband service delivered to these premises for almost ten years, supplied by six vendors: Telstra Bigpond, iiNet, Amaysim, Southern Phone, Exetel and then Sumo.
Problems were experienced with the existing Engin VOIP service and a new MyNetPhone VOIP service.
Neither worked from either of my broadband gateways' integrated ATAs, but they did work to some extent from a stand alone ATA on the internal network.
Notably, the address assigned to the outside of the gateway is a private IP address, and therefore this must be at least one more stage of address translation between the gateway and the public Internet.
Network Address Translation (NAT) frustrates VOIP which has to sense and work around the NAT scheme in use (there are no standards, implementations are proprietary), and cascaded implementations are likely to further frustrate operation.
I did manage to get the stand alone ATA to connect and handle incoming calls and outgoing calls by enabling STUN to assist the SIP addressing operations… but the connection would fail after a few days, and the only measure that was effective in restoring VOIP service was to reboot the gateway. Rebooting the gateway caused a new address assignment and obviously a fresh table of address translations in Optus' NAT box… and things worked for a few days again, then another freeze.
A fault report was lodged but there was no response after two days, this lack of ongoing reliability of the Sumo / Optus / NBN service for VOIP was reason to quit them.
It was a pity to need to quit Sumo / Optus / NBN, because download speed was consistently good.
Above is a plot of download speeds over the month of service.
As a result of behavior of the industry, the ACCC gives some guidance on terms used to advertise a service, and a service expectation.
Essentially they say:
Standard Plus Evening Speed—plans using this label will deliver a minimum speed of 30Mbps during the busy period. This plan would be suitable for a higher usage profile (e.g. streaming an ultra-high definition movie and streaming music on one or more other device during the busy period)
So on that measure, how well did they perform?
Above is a plot of speed tests during the defined “evening hours”, and it is generally very good with the exception of two recorded tests of 0Mb/s.
The integrated ATA in two unlocked gateways did not work with Sumo / Optus for VOIP services with two different independent providers. Both VOIP services worked with an independent ATA, but failed after about three days even though there was a traceroute path from the ATAs to the associated SIP and STUN servers on other ports, indicating a failure of NAT somewhere. The gateways and ATA proved reliable on the previous and subsequent access services.
Similar problems were experienced with SouthernPhone / Vocus.
Are the failures due to an incompetent / untested solution, or deliberate actions on the supplier's part to capture VOIP revenue for their own network? I have certainly encountered problems in using an independent VOIP provider with iiNet (supplied gateway locked to their own SIP server), SoutherPhone/Vocus (would not connect), and Sumo/Optus (connection failure / reliability problems).
This is not a type of problem that RSPs are likely to fix quickly if at all, and the expedient approach is to choose another supplier (that does not use private IP addresses for the gateway to minimise risk).
Experience is that although it is possible to cancel contracts without penalty when the supplier does not perform, it usually involves the TIO and that introduces significant delay during which service remains disrupted.
I have come to view that because of the wide scale failure to deliver a service as promised, one should exclude all offerings that involve large initial costs or early termination fees.