Who’s me? Parents only to ready to accept the charges when they know it’s the only way they will ever get to hear from their errant offspring will no doubt welcome a new MCI Communications Corp service chirpily called It’s Me: the service, part of its 1-800-Collect series, enables subscribers to set a blanket collect on calls from a particular party, so the caller no longer has to wait for the call to be accepted by the called party; AT&T Co says sourly that it already offers a similar service and says its own gives the called party more control trouble is, once again, Ma Bell falls down on the presentation side, because in a tussle with the dreary AT&T name of True Ties, It’s Me is the winner, no contest.