Specifies the method to use to lookup SIP servers
`eConventionalSrvr` - A configured server entry defined by IP or FQDN.
`eSrvRecordTemplateSrvr` - This is not an actual server but a template which will populate the server(s) once the SRV Query gets a response from DNS.
`eSrvRecordSrvr`- The actual server created after SRV Query."