1.
If you call someone up, you telephone them. (mainly AM)
When I’m in Pittsburgh, I call him up...
He called up the museum...
Sometimes I’d even ~ at 4 a.m.
= call
PHRASAL VERB: V n P, V P n (not pron), V P
2.
If someone is called up, they are ordered to join the army, navy, or air force.
Youngsters coming up to university were being called up...
The United States has called up some 150,000 military reservists.
= draft
PHRASAL VERB: be V-ed P, V P n (not pron), also V n P
3.
If someone is called up, they are chosen to play in a sports team.
He is likely to be called up for Thursday’s match against Italy...
PHRASAL VERB: be V-ed P
see also call-up