What equipment or devices do I need to connect a traditional

I’m new in asterisk, I have an asterisk server work and i can make connections between 2 or more PC’s, as well as communicate through SoftPhone, my doubt is, what do I need to connect that Server to a telephone switch?

I have read forums where it says I need to have a special card, but I don’t know wthat kind of card neither how the connection between server and switch works.

If you just want to use VOIP you do not need any cards. All you need is a network switch (you can use your current network). If you want to connect to the PSTN you will need some hardware.

How many lines to the PSTN are you looking for? There is a BIG difference in price between 1 and 120 so give us some clue as to how many lines and of what type they will be (analog, T1, E1, etc).