iPhone XR calls timing out (hanging up) at intervals of 9 minutes

[PirateGopher]

I initiate a Zoom conference call (audio only - not app) Tuesdays through Fridays from 5am-5:30am. Sometimes, there are no participants on the call. When there are no participants, the call will terminate nine minutes after starting. I then start the call again and again in nine minutes, the call terminates. This only happens when there is silence. No other calls I make terminate.

This happens sporadically but often enough to be irritating. I opened a ticket with Zoom in April (when this started) and they have stated the problem was not on their end after researching it for two and a half months . I also have a ticket and community post open with Verizon and Apple. Thought I would check here to see if anyone else experienced this or if there is some setting that I am missing.
My thought is that the phone, carrier or Zoom have a timeout set somewhere if there is no one speaking.
Any ideas will be very appreciated.

[CarlaA]

Hi @PirateGopher thank you for your contribution to the Zoom Community. We are so happy to have you here, welcome! Idle meetings should time out but only after 30 hours of inactivity. I would be interested in seeing if there are fellow community members who are experiencing the same issue.

Thank you for bringing this to the community!

[TomC2]

We have been having issues with disconnects from the Zoom end for almost a year. These only occur when connecting from a SIP room and happens daily. We have a ticket open with Zoom but no luck yet. It appears to be a Zoom issue because there are no timeouts when using MS Teams or in connecting point-to-point via SIP address.