I have a client with 2 remote workers and calls to or from them to the main office result in no sound. Though they can answer calls from the call queues. They also can make and receive external calls. What is also weird is that the main office, and the other 2 locations are not local to the PBX. The PBX sits in the cloud and all internal calls with phones at the main office work just fine. I have already tried the SBC at these remote locations and it doesn't fix the issue or creates a new one. Any ideas, as I cannot setup a VPN at each one. They are using Granstream Android phones.