The current Audi car phones have problems with some SIM cards. Sometimes the connection starts and aborts after a few seconds, sometimes the connection works for a full ignition cycle but fails the next time.
If you have such problems you may try the following plugin:
Simpy install the apk. The plugin has no user interface, it only shows up in the rSAP app's settings.
If it does not help you probably have a different problem. Please uninstall the plugin, create a "main" log and mail it to me