Android Video Voip Call App (to FIX Linphone network issue)

We are an android developer We have an android app that receives video calls from hardware ( intercom system). Our app uses linphone client to receive calls. - Linphone Android works perfectly over Wifi network, but when we switch to 3G/4G it stop working. No SIP registration happen or any incoming call. - Switching of network needs to work smoothly. Need to solve this problem and only expert who already solve this problem place the bid. We are an Android developer and we are looking for quick solution. DO NOT BID you're not expert on Linphone Android. Our team will assist you with anything you might need.