If my phone call goes to voicemail after ringing once, has the

More likely muted your call but they can always claim battery ran out.
Or maybe they genuinely cant take your call at the moment (movies or class or having sex with their bf, etc).

>>18702342
It probably means that yours is not the first to go to voicemail today, and he hasn't picked up the earlier messages, so the phone goes directly to voicemail