Freepbx to gateway configuration

I can call into my freepbx from a mobile through a sim/gsm gateway connected to a pstn gateway into the softphone. The softphone is configured as an extension in the freepbx.2.10.0 installed with asterisk.1.8.13. Have set and outbound route that tries various trunks to call out.
When calling from softphone, softphone indicates its connected, gateway indicators/lights for selected lines indicate its going through, but phone/number called does not ring. After a while, the softphone makes the disconnecting tone then disconnects.
Any suggestions? Thanks.

I just had a similar issue with an Epygi FXO gateway device.
It sounds like there is no Outbound Route setup on the GSM gateway.

You will need outbound routes setup in:
PSTN Gateway
GSM Gateway.

What you have failed to do though is give any identification of what devices you are using. Without this info, no one will be able to help you.
I am no expert but i have just solved this exact problem with our gateway.

Info you will need to provide will be at least:
Version of FreePBX (Distro or Vanilla install)
PSTN Gateway make and model
GSM Gateway make and model

Hope this at least helps you to get things resolved.