[Serusers] how to use check_to ?

Hello! Finally I got check_to() working well with the uri table. However I discovered, that there is a problem with some SIP UAs which does not support or not work well with SRV records. What I mean: I have a domain: example.com My SIP UA doesn't support SRV records, so I have to configure it directly to use my SIP server. Therefore the UA sends uri like xyz(a)hostname.example.com. My SER is configured to use if (method=="REGISTER") { if (!www_authorize("example.com", "subscriber")) { www_challenge("example.com", "0"); break; }; if (!check_to()) { sl_send_reply("403", "Registration id must does not fit"); break; }; save("location"); break; }; In logs I see: 0(15538) HA1 string calculated: 589858581b9363bcd477f922ff71172a 0(15538) check_response(): Our result = 'b3fcd7f8f83981c994ff52f388001415' 0(15538) check_response(): Authorization is OK 0(15538) save_rpid(): rpid value is '' 0(15538) check_username(): Digest realm and URI domain do not match 0(15538) parse_headers: flags=-1 What is the most elegant way to solve such case - together with UAs which can use SRV? Any idea, hints? Thanks in advance, Tamas