if (method == "INVITE") {
                if (uri =~ "sip:[0-9]{10}@*") {
                        log(1, "Forwarding to Proxy\n");
                        rewritehostport("10.10.15.22:5060");
                        t_relay();
                        break;
                }
        };

        if (method == "INVITE") {
                if (uri =~ "sip:[0-9]{3}@*") {
                        log(1, "Forwarding to Proxy\n");
                        rewritehostport("10.10.15.22:5060");
                        t_relay();
                        break;
                }
        };

        if (method == "INVITE") {
                if (uri =~ "sip:[0-9]{11}@*") {
                        log(1, "Forwarding to Proxy\n");
                        rewritehostport("10.10.15.22:5060");
                        t_relay();
                        break;
                }
        };

I'll refer to these as entry 1, 2 and 3, respectively.