On a BellSouth POTS line, if no long distance carrier is assigned, a
> long distance call cannot be dialed accidentally using 1 + 10 digits,
> but you can dial long distance by dialing 101 + the carrier code + 10
> digits. The only way to avoid this is to pay for a restricted line,
> which is several dollars more per month.
I think this is pretty much the norm but is somewhat different than what I was commenting on. The situation you describe would certainly NOT result in the call being assigned to a "random carrier".
> LD call should, even by accident, be placed from your phone, you may
>> find yourself assigned to a random carrier for that call, and this
>> carrier will bill you at an unbelievably high per minute rate.
As was pointed out in another reply, the only way I see this happening is if the LEC screws up and actually assigns you to a "random" carrier when you really wanted none.