When one ascends to the greatest deliberative body in the world, many pressing choices must be made: Which committees would the senator-elect like to sit on? What legislation is to be introduced?

And, most important to the constituents, lobbyists, friends and foes who clog a senator’s phone lines, what music will callers be forced to listen to while they’re on hold?

As it turns out, lawmakers have four options, which are provided by the Fort Mill, S.C.-based outfit Muzak, renowned for the tinny, re-recorded synthesizer riffs heard while in a dentist’s office or an elevator or while waiting to talk to, say, the senior senator from Mississippi.

“The whole Senate has Music on Hold,” an anonymous official at the Senate Telecommunications Office said of the Muzak service, which a company official said costs senators at least $65 per month. Options such as voiceovers cost extra. (The telecom office takes a senator’s Muzak preference seriously and considers it to be a private matter.) “You have a choice of Patriotic, Classical, Environmental and Country.”

An unscientific sampling suggests that a large majority prefer Classical to the John Philip Sousa marches of Patriotic or the Garth Brooks hits found on Country. (Nobody appears to have taken to Environmental, which one Senate aide dismissed as “whale sounds.”)

Politics and geography appear not to have much impact on music selection. Sen. Barbara Boxer (D-Calif.) enjoys Classical. So does Sen. Lindsey Graham (R-S.C.). So do Sens. Pete Domenici (R-N.M.) and Jay Rockefeller (D-W.Va.).

Conveniently, Muzak’s Classical selections tend to be conservative — musically, that is — and therefore politically safe: Mozart piano concertos, Beethoven symphonies, the occasional Brahms string quartet and Faur� nocturne. There are few, if any, avant-garde or potentially offensive pieces of music — for example, Richard Wagner’s “Flight of the Valkyries,” thought to be a favorite of Adolf Hitler.

For some senators, their choice of on-hold music is a natural fit.

Sen. George Allen (R-Va.), for instance, who has built his whole political career on his good-ol’-boy folksiness, favors Country. The senator’s press secretary, David Snepp, said of Allen, perhaps the Senate’s only Johnny Cash aficionado: “Anybody who knows George Allen knows it’s country music all the time.”

Sen. Thad Cochran (R-Miss.) prefers “instrumental classical,” one of his aides said. (Presumably, the senator has banned Don Giovanni from his phone lines.) No surprise there. Cochran is a pianist who keeps a Kurtzmann baby grand in his office and occasionally performs for staffers.

Sen. Hillary Rodham Clinton (D-N.Y.), whose job entails, among other things, representing Carnegie Hall, Lincoln Center and Juilliard, also prefers Classical. While on hold recently, a reporter from The Hill was transferred from an office assistant to a Bach partita to another assistant to a Corelli concerto to a press secretary’s voicemail.

Boxer, sounding just a bit like a senator from a blue, coastal state packed with writers, musicians, movie producers, Hollywood starlets and sundry snobs and cultural elites, informs all those who dial her D.C. office: “If you wish to stay on line, you will hear classical music.”

Still other senators, consumed by the people’s business, don’t pay much attention to such office details. “Seeing that the senator will never be put on hold in his own office, I’m sure he doesn’t even know what kind of music he has,” said Rodell Mollineau, spokesman for Sen. Mark Pryor (D-Ark.).

Meanwhile, some senators, taking a no-frills approach, shun the whole business of hold music. They prefer to make their callers listen to nothing. The barebones set includes Sens. Jack Reed (D-R.I.), John Warner (R-Va.), Herb Kohl (D-Wis.) and Kay Bailey Hutchison (R-Texas).

“He’s a traditionalist, and there was no music on the phones when he came to the Senate 28 years ago, and he likes it that way,” Warner’s spokesman, John Ullyot, said of his boss.

Said Greg McCarthy, Reed’s spokesman: “The preference for Senator Reed would be to have a very short hold time. He’d much rather have people on the phone taking care of constituents.”

Muzak marketing-campaign coordinator Karen Vigeland suggested the no-music policy may be bad politics. “A lot of people think they’ve been hung up on if there’s absolute silence,” Vigeland said. Not smart, she offered: “You want to show that you care.”

Vigeland added that 70 percent of all calls placed to businesses (including government agencies and congressional offices) are put on hold and that the average hold time is 50-90 seconds. At any given moment, more than 1 million people in the world are waiting to speak to someone. According to Muzak’s website, 100 million people around the globe “experience us everyday.”

The Senate is not Muzak’s only Washington contract. Other clients include the White House, the Pentagon, the Justice Department, the CIA and the Republican National Committee, Vigeland said. Members of the House of Representatives also can order Music on Hold, but many, if not most, have opted out.

Jason Roe, chief of staff for Rep. Tom Feeney (R-Fla.), explained, “There are two reasons [the congressman doesn’t have Music on Hold]: One, it never occurred to us that we could have music when people are on hold; two, we don’t put our constituents on hold. We take care of them right away. I get put on hold when I call my friends on the Senate side. They’re too busy doing nothing.”