I have ser configured and workin fine with multiple domains.
 
I assign an unique numeric alias for each user not realted to the domain. So If I have an alias 0823384@domain1.com can't have 0823384@domain2.com link to another user.
 
Now I'd like to let the user of doamin1.com using the regular phone to call the user of domain2.com trough SER (I am using 0.9.2);
 
I am not able to figure out how to modify the ser.cfg to accomplish this.
Could I rewrite the uri if I don't find the alias and let them find again with the new domain? 
Something like this:
if (!lookup("alias")){
        if (uri=~"domain1,com") {
                rewritehost("domain2.com");
                lookup("alias");
                # if it is not about the other domain it come back
                if (!lookup("alias")){
                    rewritehost("domain1.com");
                }
        } else if  (uri=~"domain2,com") {
                rewritehost("domain1.com");
                lookup("alias");
                 # if it is not about the other domain it come back
                 if (!lookup("alias")){
                    rewritehost("domain2.com");
                }
        }
  }
 
Hope o receive some feedback.
Thanks