What's app calls no ringtone

[danizzz]

Hi everybody
I have big time troubles with what's app call on my iPhone 6.
When I receive a call via what's app, a lot of times, It doesn't ring the ringtone and I lose the call. Appear only the notification on the screen during the call but without sound. My IOS is 6.2.

 

[RogMoore]

You should check the settings, might not be set the ringtone.

 

[danizzz]

Settings are ok ringtone is on. It seems like sometimes there is no sound when I receive a what's app call.