sth to clarify -- i missed a call from HP

I missed a call from HP this morning; when i called back, couldn't figure out what was happening becuase it is a general line (many ppl use the same phone number);

my friend said it might be a call for interview;

just wanna ask--
(1) if they wanna call for interview, will they necessarily send emails to notify us? or
(2) they might just make a phone call without sending emails?

thanks