Phone Extensions... causing calls to fail - no validation shown

When you add a phone number in phone or mobile field AND also an extension, then use salesmate dialer fails to dial the number. It brings up the phone dialer and looks as if it's actually dialing but nothing happens.

I've tested this on multiple records and phones and its easily recreated bug. 

There should be a field validator that prevents extensions from being added to phones. Or perhaps do not allow dialing at all when extension is present and warn user when they try to dial the number that it can't because it has an extension etc.