Some of our data SIMs are failing to connect. The problem actually started on Friday and has been confirmed today. This is affecting our data-only SIMs, and not our sip2sim's.
Upon further investigation, this isn't actually a problem with the carrier, but a problem on our side. This is affecting a small number of SIMs, we're still investigating.
SIMs are now able to reconnect. This was affecting SIMs configured in a particular way. It affected SIMs that had a single WAN IP assigned on the SIM settings page, those that were associated with a 'Line' on the control pages were not affected.
There remains a problem with the IP address being allocated to data SIMs where there is more than one SIM on a login (eg xxx@a). It seems all SIMs (regardless of them having a line or not) are being allocated the same IP. This is being investigated.
We're deploying a fix for this at the moment which has solved this issue.