[OpenSER-Users] LCR module: missing the link between lcr and gw

I have read and re-read the overview of the lcr module but still think I'm failing to understand it. What I want to achieve is routing to different gateways based on number dialled e.g. 001, 0044, 0086 should result in different gateways. Looking at the tables, I would guess that the link is lcr -> gw_grp -> gw as shown in the following example: lcr prefix from_uri grp_id priority 001 1 1 001 2 2 0044 3 1 0086 4 1 0086 5 2 gw_grp grp_id grp_name 1 US 1 2 IS 2 3 UK 1 4 China 1 5 China 2 gw gw_name grp_id ip_addr port uri_scheme transport strip prefix A 1 192.1 5060 1 011 B 2 192.2 5060 1 011 etc I don't think I have understood correctly because the documentation implies that gw_grp is optional. Is there a tutorial for this module that could calrify my understanding? I'm also trying to understand what the various avps are used for. Any advice appreciated. Regards Cameron