Fax modem - E1 line - Sangoma 200 gateway

I am using Freepbx 5.211.65-21 with a sangoma Vega 200 gateway for my E1 line
(200 DID’s,xxxxxxx500-699 ).
Everything is working great.
Now i need to use 1 DID for example 599 to receive incoming fax’s.
When i receive an inbound call on xxxxxxx599 ,that call should be redirected to the fax modem.
When an extension in the office receives an inbound fax call he has to be able to forward that call to the fax modem extension (599)
I am totaly confused.
Should i buy the sangoma 50 fxs-fxo gateway ? and how can i use it ?
Can someone please give me some guidelines on how to make this work ?!!
Thank you