Learn Russian: Мой друг часто звонит.

The dictionary form of this verb is звонить (to call). Because it ends in -ить, it belongs to the second group of Russian verbs (second conjugation). To say "he/she/it calls"—in this case, "my friend"—we drop the -ить and add -ит, giving us звонит.

Why is the word order часто звонит instead of звонит часто?

While Russian word order is very flexible, adverbs that describe how often something happens—like часто (often), редко (rarely), or всегда (always)—most naturally go right before the verb they describe.

If I want to say a female friend calls often, how does this sentence change?

You would change the first two words to the feminine form: моя подруга. The rest of the sentence stays exactly the same! Verbs in the present tense change based on who is doing the action (I, you, he/she/it), but they do not change based on gender.

Can I use звонит to say my friend is calling out my name?

No, звонить specifically means to call on a telephone, or to ring a bell. If someone is shouting your name to get your attention, Russian uses a completely different verb.