"Jag har försökt ringa dig."

Translation: I have tried to call you.

[SKWARDOL]

är det okej om jag ska lägga ordet "att" före ringa dig. sorry for my broken swedish

[Lundgren8]

Yes, that also works.

[Ryan4090]

Ringa vs ringa upp?

[JoakimEk]

There are overlap, bit I'd say "ringa upp" is more focus on dialling and initiating a call, and "ringa" the whole thing with the conversation.