[Serusers] uri matching for dial plans

Hi I have a nice table of prefixes and gateways, which works great using lcr, however I am now working on dial plans, i.e user can call 001, not 0044 etc etc, based on what I have in my grp table. Problem here is with codes like 001 since this would allow 001234 also, which for instance could be puerto rico (which it aint) but if it was I wouldnt want the call to go there. so I am doing something like if (uri=001 && !uri=001234) make the call...BUT this is a pain, especially for 001, I have had to block out 30 odd routes manually, which is making my ser config look really ugly. add into that other routes and suddenly we have a painful config file. So what I wanted to know is it possible to pull info from a DB, using exec, and store the value in a variable which can be used later. the grp table only really allows u to bind a "name" and then see if the from user is in that group, but it dont let you to the break that down into finer options, especially dial plans Iqbal