Thanks for the answer! What if the aother practice wants to use the same number you use for your own practice?

Answer 1

Such an effort would be a violation of Federal Law with considerable potential penalties which should theoretically discourage such a practice. One can never be certain. It could happen by accident, or as an oversight. Dr A may have been filling in for Dr B and if Dr B was going to pay Dr A then Dr As work would be billed under Dr Bs number. Confusing? That is why we have one individual in the office who deals solely with billing.