Fully Committed may revolve around the bad workday had by Sam, a reservations clerk in a trendy New York restaurant, but playing the much-put-upon fellow is a marvelous job for an actor. And both poor Sam and the actor portraying him provide an enjoyable time for the audience attending the Philadelphia Theatre Company production at Plays & Players Theatre.

It is difficult to separate how much of this play's entertainment comes from the script and how much from the performance. The play, a first effort by Becky Mode, is a keenly observed, nicely turned one-man farce. While Fully Committed's gimmick of someone talking nonstop on the phone for an hour and a half can wear a bit thin, the knockout performance by Kraig Swartz under the able direction of Gus Kaikkonen is engrossing.

Swartz has taken on an incredibly daunting role. He not only portrays an aspiring actor named Sam Peliczowski, who to support himself takes phone reservations at a restaurant everyone wants to get into, but he also voices the raft of other unseen characters, male and female, to whom he talks on constantly ringing phones.

Just committing to memory the multitude of brief, constantly changing bursts of dialogue with himself and delivering them flawlessly - while creating and re-creating colorful characters (these folks keep calling back) - is fascinating to watch. He's like a juggler keeping more objects in the air than anyone should, and you keep waiting for him to slip up. The night I attended he didn't once.

Sam's day is bad from the start. As he descends the circular staircase to the basement phone room of Nick Embree's carefully detailed set, the phones are ringing madly and he quickly learns that his boss won't be in to help. Donning a headset so he (and the production) is not tied to a phone cord, Sam goes to work.

Those he talks to on the phone include, of course, people who in an attempt to get a table use ploys ranging from outrage ("I can't believe you lost my reservation!") to tearful pleading, to outright bribery. He also must deal with the restaurant's obnoxious, self-centered cook-owner; the smarmy French-intoned maitre d'; a fellow actor gloating over a job he thinks he got that Sam didn't; his widowed father in Indiana who wants him home for Christmas; and Zagat, of the influential Zagat restaurant guide, arriving for lunch and finding his reservation has been misplaced.

Mode's comic situations are inventively constructed and she maintains enough of a plotline to keep the audience interested in and rooting for the awfully nice guy Swartz makes of Sam. But Fully Committed is in the end light theatrical fare that can be compared to partaking of a skillfully prepared and presented appetizer: It doesn't leave you completely satisfied, but there's no doubt you've had something tasty.