This information is provided on the understanding that your adapter is correctly configured and not forwarding incoming calls to voicemail but your phone is not generating an audio alert.
Log into the PAP2 adapter, as the Advanced Admin user, and under the Regional Tab Misc tab;
You need to change the FXS port input gain from -3 to a figure like 1.0.
The maximum figure you can change this setting to is 6.0
We suggest you experiment to get the right setting for your device.