Taxis with meters are available in almost big cities. The current price is about US$ 0.5 per kilometer. Most metered taxi drivers can speak a little English.
110-220 volts A.C
Long distance calls should be made at post offices, hotels or telephone booths (phone cards are available at post offices). Normally, hotels will get 15-20% service charge of the bill. Internet phone is an alternative choice and much cheaper, with around 0,1USD/minute to Europe or America. Prepaid sim cards are very popular and cheap everywhere ( 0.08 USD / minute for domestic calls. Vietnam cell-phone networks are GSM and Vietnam operators have roaming agreement with most countries in the world.
Internet cafes with ADSL can be found easily in Vietnam. Surprisingly the cost for an hour is as very cheap as around 0,2US$.
Tipping is not obligatory in Vietnam, however, if you meet with exceptional services or kindness, a tip is always appreciated. A tip for good service might be about 5% of the bill.
Bargaining is a way of life in much of South East Asia. In Vietnam shops don't have fixed prices so the shop keeper will start with a high price which you are then expected to bargain down until you reach a fair price. Bargaining should always be relaxed and can be a lot of fun but you should remember that it is considered disrespectful to agree a price but then walk away.