Is Area code 636 long distance to call area code 314?

Area codes 314 and 636 are adjacent, so it is likely that many calls between them are local, but there may also be some toll calls.

The easiest way to find out is to dial the number with just the area code and number (without the "one plus" at the start). For example, dial just 314-555-0123. If the call goes through, it's local. If you get a recording telling you to hang up and dial 1+, then you know it's toll. (This works in Missouri and many other states, but not in some other states like CA, NY, IL, etc.)