Making FreePBX work with Gempro GSM Gateway

My PBX Setup consists of following components

  1. FreePBX
  2. Gempro GSM Gateway for dialing out GSM

Following extensions are setup

  1. 900 - My extesnion
  2. 0 - Gempro gateway

Gempro has a feature called “1 Stage ( Called Num.)” by which whenever the calls land with the dial digits, the gateway just initiates an outgoing call with the same number.

For this I have created an

  1. An Custom Trunk with dial command "local/0@from-internal.
  2. An outgoing route with a dial pattern any number starting with 0 to be routed to the custom trunk

The calls are successfully getting routed to the 0 extension of gempro gateway but when we enable the “1 Stage ( Called Num.)” , gempro just dials out the number in GSM as “0” as that is the dialled digit it is getting from trunk.

Could anyone please help out on how to fix it.

I am using hosted:
Asterisk 1.6
FreePBX 2.10
A2Billing : 1.9.4

I am interesting to buy Gempro 712 2 channel. I want to use this as mobile access number, i have calling cards system which is working. In my country mobile to mobile is free, so I am thing to offer my customers a mobile access number. So i need to know how many simulteneuscall can this make if i connect to my server as DID number ?
if anyone has experience about this device please answer for me.

I understand Gempro 712 2 channel can by default 2 simultaneous calls. However even i am new to device.

If any one else is facing the issue, you can put the Custom Dial String as “SIP/$OUTNUM$@0,60,r” and user 1 stage dialing in Gempro

I know 1 freind who is using Goip, he connected goip to his server as access number, when he Enabled Call waiting, it worked like this:
When you make call at the sometime from 2 different cell phones one of then gets buzy, but if you call after when the 1 call “a2billing” answered the second call a2billing will answer also.

I dont know if gempro can work like this.