Receiving face book/whats app messenger call put my mobile in vibrate mode

[suny1983]

When I receive any messenger call and accept it for 2 or more time my mobile goes to vibrate mode.Restarting it resolve the issue but again if I receive messenger call for 2-3 time same

happens again this happens for whats app and face book messenger only not with hangout or other mobile call.I am using Panasonic P55 Novo 4G with Marsh mellow .

Any kind of help from your end is highly appreciated .
Thanks in advance.

 

[sk17526090]

Phone update