Hey guys, I've now received an update from Networks. I've been advised the following:
There is an issue with roaming reliably in India at the moment per incident report - 17501904. The issue is still under active investigation with no firm ETR but is believed due to intermittent congestion on our direct international signalling links between Optus and Airtel/Bharti.
This issue is in part due to a recent undersea (AAG) cable break which has reduced link capacity.
Networks are currently awaiting an update from Singtel who they have escalated to for further investigation/action.
I'm happy to send through updates as they come our way.
Ah, thanks for the update @Simk.
I've been advised that the issue is intermittent. As far as a permanent fix is concerned, we've been advised of an estimated cable repair date of early - mid January.