[Serusers] multiple domains

Hi, i have a little problem i am using modparam("usrloc|registrar|avpops", "use_domain", 1) i have few domains ..for example xxx.com yyy.com zzz.com i also done some numbering plan and: for xxx.com have 10XX yyy.com have 20XX zzz.com have 30XX i want to users from xxx.com can "ring" to yyy.com using sip:20XX@yyy.com or just 20XX(a)xxx.com the problem is how to setup route any connection going to numbers like 20XX from any domain will go to domain yyy.com now i have done it with aliases so i put 2001(a)xxx.com --> sip:2001@yyy.com but this suck any one can tell me how to rewritedomain in uri ? using rewritehost is good for forwarding call to other sip server .. but those domains are all in one additionally there are things like sameusername(a)xxx.com sameusername(a)yyy.com and all subscribers are in one mysql table so this must be done using some route trick. Can anyone have any idea?