What is voice chat on MSN messenger?

If you mean Windows Live Messenger, then yes, it contains the ability to do both. You can use it to talk to another friend without using video. It just requires having a microphone connected to the computer. If you have a webcam, that can also be activated, but it is up the the user on whether to use it or not.

There is another cool device that you can chat with anyone you want. It’s called a telephone, and you don’t even have to use the computer to use it!

That’s like Skype, right?

@zensky Yes, it is very similar to Skype.
@filmfann Ah, but using WML is not only free (an advantage when your partner lives in another country), but images and links can be shared while conversing, games can be played, and bathroom breaks are not taken within earshot.

@filmfann the disadvantage of the telephone is you have to pay for your calls (either by the minute or as part of a contracted allocation of minutes). VOIP (voice over IP) such as Skype or MSN is free.