The Nvoice Mobile client has its own standard ring tone. I.e.. if the Nvoice Mobile client is open and connected to a WLAN and a call comes in, this standard ring tone is used. Change the standard ring tone in the Nvoice Mobile client settings. However, this is not advisable! When a different ring tone is selected and the Nvoice Mobile client is running in the background and connected to a WLAN and a call comes in, the standard ring tone is always used, not the customised Nvoice Mobile client ring tone. I.e., you only hear your customised Nvoice Mobile client ring tone if the client is open and connected to a WLAN and a call comes in. Furthermore, you hear your iPhone ring tone if a call comes in on GSM. I.e., if you are not connected to a WLAN or the Nvoice Mobile client is not running in the background.

Conclusion:

You generally have 2 different ring tones. A ring tone for WLAN calls and a ring tone for GSM calls. If the standard ring tone in the Nvoice Mobile client settings is changed, it is possible that you have 3 different ring tones.You then have the standard ring tone when a WLAN call comes in and the Nvoice Mobile client is running in the background and the customised ring tone if a WLAN call comes in and the Nvoice Mobile client is in the foreground.You always hear your iPhone ring tone for GSM calls.