I registered my sip account on my iphone's zoiper.
It works fine if the incoming call is from landline or mobile phone.
But if my friend call my from their zoiper sip account, I can't hear their voice until their shout to me.
Even if their shout to me, the voice sounded very small and far (quite sure the phone voice is the loudest one).
I've try the way the Q&A said, but remained the same situation.
If I registered my account on android phone, the incoming sip call voice is smaller but OK for hearing, and I still can use the function, "Speaker Gain“, to make it louder.
The zoiper app on iphone seems to NOT have this "Speaker Gain" function, what should I do?
