It is best to call a taxi if it is an option. After you request the taxi, stay on the line and the operator or a recording will tell you the license plate number of the vehicle that will service you. It is a good idea to take note of the plate number and match it to the taxi that arrives. All phone-requested will require that you tell the driver the "clave", which is the last two digits of the phone number from which you called the taxi. However, it is not always possible to call for a taxi. It is very difficult to call a taxi between the hours of 5pm and 8pm from Thursday to Saturday, or when it is raining heavily. Taxis often have trouble changing large bills. You wonder why? We wonder why, too. At most, try to pay with a $10.000 bill for shorter rides, and a $20.000 bill should be fine for longer rides. Also, try not to slam the doors of the taxi (or any cars for that matter) as Colombians are very sentive and are affraid it will break their car.
If you must take a taxi in the street, be sure to be cautious. Taxi robberies are not frequent but they do happen. There is no sure-fire way to tell if a taxi is counterfeit, but there should be a meter running and it is not normal for a taxi driver to be talking on his phone a lot. A trick is to make a fake phone call from your cell phone and say out loud the plate number and the taxi number you see in the window. Know that there is a small surcharge if you are picked up at night, if you call, if it is Sunday or a holiday. This means if you call a taxi on a Sunday night after 8pm you will pay about $3.000 on top of the base price. Always make sure that their meter starts at 25 as they tent to take advantage of foreigners. It also happened to us a few times where the meter of a taxi was modified to change faster. Unfortunatly, this one is hard to catch as you need to know the usual cost of your destination to make sure you are right.
Here are a few numbers you can call. There are many more to choose from, but these are the main ones. If you are calling from a cell phone, make sure to dial 031 before any land line numbers.
211-1111, 311-1111, 411-1111, 711-1111