To call the USA, Canada or PR from Costa Rica is rather simple and painless. The telecommuniation sheme in the country is wide, modern and very flexible.
Although VOICEIP is pretty much predominant in the country, you may still use copper lines to make international calls.
To call the US simply dial 1+ area code+ number. To call Canada and PR pretty much do the same.
If at any point you feel you can't proceed with the call or the same isn't working, simply dial 1024 to get connected to a bilingual operation who will assist you.