We spent two months in Guatemala visiting Tikal, Semuc Champey, Rio Dulce, and Lake Atatlan. Tigo worked with 3G connectivity in every place we were. The only reason TIGO has a B and not an A is that at times the service would be down for several hours. Guatemala doesn't believe in 99% uptime or if they do then they don't follow it. I would get a TIGO chip anytime I was visiting Guatemala.