Using POTS line as a main line for multiple calls?

If I was to use the same main line as we use now from Centurylink (POTS phone company) and through a Atcom fxo / fxs card translate to voip can it still receive multiple calls without a busy signal?

I am using Asterisks and freepbx.

Nope. You can still only handle one call per analogue line.