The main languages spoken are Tibetan, Chinese, and English.
The local currency is Chinese Youn. Credit cards are generally accepted in bigger towns and at hotels. There are ATM's in the larger towns.
To call internationally from Tibet, dial: 00 + country code + area code + telephone number. Hotel receptionists will help you make calls.
Only global cell phones will work and only in the bigger towns. You may want to consider renting one or getting a satellite phone.