The international dialing code for Bhutan is 975
WiFi is readily available in the majority of hotels around the country. Most cybercafés also offer Wi-Fi. Most population centers have cybercafés, although they are relatively expensive, and the connection is slow. Please make sure your travel agent finds a suitable cybercafe in advance if you need a connection for the job.
Telephone booths exist in the big cities of Bhutan
Most of Bhutan has a mobile phone coverage, which is capable of smart phone. B-Mobile has agreements with countries in North America, some countries in Asia and Europe on mobile roaming. Tashi Cell is another mobile phone company based in the country.
Tourists can now register quickly and easily to a valid B-Mobile SIM card for one month. Just take your passport to a B-Mobile office. The SIM card costs 50Nu and has a credit of 50Nu. Ask them to enable 3G and data access while you're there, and test it before you go. There are no data plans per se, but the rate is affordable by international standards (0.0003Nu / KB). The only available SIM card size is the standard size, but some desks have sim cutters for the iPhone 4 and 5 (if you are worried, bring your own SIM cut). B-Mobile recharge cards can be purchased at most general stores.
The official tourist office of Bhutan is the Bhutan Tourism Board, for more information on the destination you can find on this site.