SIPS SRV lookups bug

[michael-salient]

I'm trying to call a WebEx SIP URI:

gophone -t tcp dial -media=audio sips:[email protected]:5061
Sep 19 09:25:30.561 INF Dial > Listening on transport addr=192.168.1.167:54387 protocol=tcp
Sep 19 09:25:30.561 INF Dial > Network ready
Sep 19 09:25:30.577 INF TransportLayer > IP addr resolving failed, doing via dns SRV resolver... error={"error":"lookup example.calls.webex.com: no such host","kind":"*net.DNSError","stack":null}
Sep 19 09:25:30.682 WRN TransportLayer > DNS resolution is slow dur=107.773167
Sep 19 09:25:30.683 ERR Dial > Call failed error={"error":"failed to create client transaction: fail to lookup SRV for \"prestigefinancial.calls.webex.com\": lookup _sip._tcp.example.calls.webex.com on [2600:1700:464:9400::1]:53: no such host","kind":"*fmt.wrapError","stack":null}
Sep 19 09:25:30.683 INF Dial > Closing dialog

There are SRV records under _sips instead of _sip: _sips._tcp.example.calls.webex.com

There should be a way to flag it, or it should guess from the sip uri.

Thank you for making this tool, it's very helpful for simple SIP call testing!