We have had some reports today of some calls not getting to phones, this is being investigated.
This looks like an issue with ONSIM and the carrier and us having multiple live servers. This seems to make things less reliable. We are testing configuration changes now.
It looks like there is a flaw in the carrier handling of multiple servers, well, in that they don't seem to, at all (for calls to phones). We're looking in to getting them to fix that. In the mean time we are making a change to prioritise one server as a workaround for now.
Ok calls both ways failing right now, working on it.
Calls from mobiles back, using a priority server. Waiting on DNS catch up for calls to phones now.
It is clear they are not honouring our TTL, so still waiting.
Seems like they are assuming something like 1H TTL, which is a pain, but calls working for now. We have to work with the carrier to resolve this properly without forcing one priority server, so we have the redundancy we normally expect.
For now, one server in use, until we sort multiple server handling with carrier.