In college, one company woke me up with a phone call at 7 AM to reject me. They were even in the same time zone!
Ouch. Talk about adding insult to injury (or, at least, mild inconvenience). At least in my case, they scheduled the call, which avoids being woken up or otherwise interrupted, but prolongs the agony a little.
At least do SOMETHING. Perfectly fine with an email.