Viber messenger Porblem

Dear All
hi
I’m one of ISP in Iraq and i have big network Depend on mikrotik system
and i have 3 internet Resources 2 fiber optic and one on VSAT
my problem is with any VOIP program and Viber messenger on I phone and android
any one have same my problem and he can fix it
thanks for all

dose any one have this problem with viber messenger
i’m talk is there any firewall filter can add in mikrotik to fix this problem