Hi,
I've recently noticed that there is a daily usage of mobile data by Zoiper. This takes place even while connected to wifi. This data usage seemed to happen daily just after midnight local time. In an effort to stop this, I tried disabling mobile data overnight. This only served to delay the data usage. Shortly after enabling mobile data in the morning, the same data usage would take place. Typically this uses about 10-20MB per day. I'm using the paid version of Zoiper Gold on Android 7.1.1. Just upgraded to Zoiper version 2.2.53, but haven't confirmed if this behaviour continues. I've disabled the access to mobile data for Zoiper.
Any ideas about what Zoiper is doing, and why it insists on using mobile data, despite being connected via wifi?