When a television network has to find a way to distinguish between one of two shows on their primetime schedule not-so-loosely based on “Saturday Night Live” (which remains on their late night schedule), additional chores for the cast might be required, as the New York Times’ Jacques Steinberg explains.

Tens of thousands of fans of the NBC show œ30 Rock (or their friends or colleagues) have had the unusual experience over the last week of picking up their phones to hear the voice of Alec Baldwin addressing them by name and wishing them a happy holiday.

While the messages ” reminiscent of get-out-the-vote efforts known as push polls ” are obviously recorded, Mr. Baldwin can also be heard relating details about the recipient, like the person™s job (including the fields of public relations or pharmaceuticals) and hobbies (cooking, doing crossword puzzles), as well as complimenting his or her physique. (One choice: œI am not above telling you, you have a nice behind.)

The promotion, using the fledgling technology of a company called Varitalk, is being mounted by the NBC Universal Television Studio, which produces œ30 Rock. In a telephone interview yesterday, Shelley McCrory, senior vice president for comedy development at the studio, said that she and her colleagues had been seeking a way to give the freshman comedy an edge over its tough competition at 9:30 on Thursday nights, including the veteran dramas œGrey™s Anatomy on ABC and œCSI: Crime Scene Investigation on CBS.

The idea of making available customized messages to be transmitted by phone or e-mail ” in this case accessible via www.nbc.com/30Rock ” was inspired by an earlier Varitalk campaign, in which Web users were able to send messages using the voice of the actor Samuel L. Jackson, who was promoting the movie œSnakes on a Plane.

Still, those who have received the messages, which sound so seamless, have surely been left with a more pressing question: How do they do it?

People who try to send such a message quickly discover that it is like the old, fill-in-the-blank children™s game of Mad Libs. During a session in a Manhattan recording studio that lasted just a half hour, Mr. Baldwin recorded about 500 first names ” including such potential tongue twisters as Fowzia ” from which the sender may choose. (Choosing a name that is not on Mr. Baldwin™s list will sometimes prompt an error message from the Web site, advising the sender that it could not be found.)

Mr. Baldwin also recorded the names of all the states (so that the message makes reference to where the listener is sitting) as well as entries for drop-down menus that give the sender choices for pinpointing the recipient™s job, interests and œphysical traits. Then a computer synthesizes all this information for a greeting.

In the event things don’t work out for “30 Rock”, Baldwin might look to add his dulcet tones to the all-star roster at Hollywood Is Calling. They’ve never quite gotten over the loss of Tom Candiotti.