SRV Records need validation
myDNS is really picky regarding SRV records. If the service record does not contain "3 space-separated values" then mydns throws a seg-fault when the zone is checked or transferred. If the service record is only one value (sip.example.com), ISPConfig accepts it but myDNS does not like it. A workaround is to add 2 spaces in front of the single value ( sip.example.com) and mydns is happy again.