Trixbox: setup calling card billing using different trunks


Ive setup my calling card system on a2billing using 1 trunk(varphonex) and its working fine . Users dial 0844 then they are prompted for a card number, once authenticated, they dial 011(number) to a call.

I want to add more trunks to take advantage of LCR. I have a GSM 1 SIM module which i want to include as a trunk. This trunk should capture all numbers dialed as 011254 72X XXXXXX and forward to this GSM module in this format X72X XXXXXX as it excepts it this format to make it local.

1] How do i enter this additional trunk so that calls 011254 72X XXXXXX are routed to this second trunk?
2] Can all trunks share 1 common prefix i.e 011 but a2billing does the routing depending on the trunks LCR?