At a hotel in London, the receptionists phone rang and he answered the phone. There was a voice on the other end Tutitutututu!. He had no clue what the other person was saying so he hung up. Then the phone rang again with the same phrase Tutitutututu! and the receptionist hung up again. The 3rd time the phone rang with yet another Tutitutututu! and this time it drove the receptionist crazy. He slammed down the phone. A few minute later, a man came towards the receptionist and yelled Hey, do you understand English? I have said three times to: Bring two cups of tea to room 222! Two tea to 222.The funny story above implies to introduce to you some initial consonants and their use in Vietnamese. This table gives you some example:
Letter Similar sound in English Example
t(*) t in stay

ti-vi
th(*) th in Thai

thư
tr(*) tr in try

tr
v v in vet

v
(*) t,th, tr in Vietnamese are not pronounced the same as they are in English. They are pronounced with a flat voice without a blow-out while t, th, tr in English is pronounced with a blow-out.