Sip configuration for Elastix, for Terrasip (Provider) with Multiple DIDs

I have just purchased several DIDs with Terrasip I have configured my Elastix (freepbx) SIP trunk according to their suggestion:

Please follow this template configuration. (valid for outbound/inbound traffic)

Outgoing trunk name ***terrasip***

username=***sip_key***
type=friend
secret=***password***
host=terrasip.net
fromuser=***sip_key**
context=from-pstn ;(or set which is your inbound context) allow=g729,ulaw,alaw
trustrpid=yes
sendrpid=yes
canreinvite=no
insecure=very

;Add the follow line:
; register the user in order to receive inbound call for your sipkey

Registration String:
***sip_key***:***password***@terrasip.net/***sip_key***

Where ***sip_key*** - customer sipkey account
and***password*** - customer password

Outbound calls work, and so do inbound, but I can't route DIDs to multiple IVRs since all calls are received with the following context: sip_key@from-trunk:1

I tried mapping the route from terrasip to DID_NUMBER@mypbxserver.com
but when I dial, nothing arrives at my pbx.

I have already googled and found This Solution it proved faulty as even after the custom-inbound processing my DID is somehow the SIPKEY.

I have contacted their support and yet to get a reply, I will hopefully update with their reply, but in the meenwhile I would like my phone to work.