Attempting to call people while they are calling you makes niether call go through

### Steps to reproduce

On any Element client (tested on Element Android and Element Linux), attempt to call someone at the same time that they are calling you.

### Outcome

#### What did you expect?
"This call cannot be placed at this time" or "Caller unavailable" while one of the two people receives the other's phine call successfully

#### What happened instead?
Both calls attempt to ring, but niether person is able to answer. Sometimes this will result in an "answer/decline" prompt where niether button does anything.

### Your phone model

Oneplus 6 and also desktop.

### Operating system version

Android 13 and Arch Linux

### Application version and app store

1.5.20 F-Droid

### Homeserver

matrix.org

### Will you send logs?

No

### Are you willing to provide a PR?

No