Have you traveled to a foreign country and used your cell phone? What plan did you use?

Did you use your current cell phone plan, but add on service for the country that you went to? Or did you purchase a "sim card" for the country that you went to and plug that into your cell phone? Just wondering what option to use.

Updates
+1 y
OK when I got to Mexico, I got a text from my cell carrier that I would be covered there for an extra $5 per day while I was there. So I was able to make calls and receive calls, and text, with no additional charges besides the $5 per day. HOWEVER I got a few phone calls while I was on the ship, while at sea, I answered those calls. I ended up being charged $2 a minute for those calls!! Had something to do with the ships cell phone transponder and not being on the cell towers in Mexico.
Have you traveled to a foreign country and used your cell phone? What plan did you use?
Post Opinion