Remote calling

Hello,

I would like you to assist me with making a call via FreePBX from a remote user (200) to another remote user (201). I have a Zoiper softhpone setup one two devices some 30 kilometers apart and the internet connection where they are based gives between 20-100MS in ping to the FreePBX server at the office. When user 200 calls 201, the call doesn’t go through to 201. When either 200/1 call other extensions that are office based, the call goes through to the dial extension (say 205) but the recipient cannot hear a single word from the remote extension.

Also, when we try to transfer calls from clients, they get disconnected 8 out of 10 times.

Please help.