we are using ucm6116 in our office. We are using this system and so good. We are using voip application (Zoiper) on our phones. There is no problem with this software when we are using same wireless connection.
But when use cellular internet connection on our phones connection established with our device and calling. When a user called me i heared their voice but they can nor hear me.
Please say to me which ports must bu forwarded for this operation ?