In an abandoned greenhouse behind a concrete housing complex on the edge of the Iranian capital, there is a rock band looking for a big break.

The six members of 127 gather to practice in the early evenings, after their day jobs, when the heat dies down. They pack themselves into the airless space just large enough for stacks of battered amplifiers, the drum set and the rest of the instruments. The trombonist stands at a careful angle so as not to poke the keyboard player in the head.

They sing sometimes doleful, sometimes angry rock-and-roll in English, songs they wrote with heavy overtones of Bob Dylan, Dire Straits and Radiohead. They picked the name at random, preferring a number because it would work in English or Farsi. There aren't too many bands like this in the Islamic Republic of Iran.

Nightclubs are illegal here; the father of the 1979 revolution, Ayatollah Ruhollah Khomeini, declared that "there is no fun in Islam." So the only gigs around are either secret showcases or tightly controlled concerts.

Though the band's been around for four years, it's still waiting for official approval from the Ministry of Islamic Guidance. It's a tough business, even if you are the hottest underground band in Iran today.

"Nobody else is playing here in Tehran because, probably, nobody else is stupid enough," said lead singer and guitarist Sohrab Mohebbi, a 24-year-old with the long hair and sinewy stoop of Iggy Pop.

"If we get some money, the first thing we'll do is buy a better sound system," he added.

A few months ago they thought they had their break. On a whim, they sent a six-track demo to the South by Southwest Music Conference in Austin, the prestigious annual American pilgrimage for bands, critics and the recording industry.

But 127 faced more than the usual obstacles. The United States hasn't had an embassy in Tehran since a group of Iranian students seized it in 1979, setting off a 15-month hostage crisis. Today, the old embassy is a neglected museum known as the Den of Espionage, and some of the old hostage-takers are government ministers.

So it was more than a small surprise when Mohebbi and the others got word that they were accepted at South by Southwest. Festival organizers billed it as the first time an Iranian rock band would perform in the United States since Iran's revolution.

The band cobbled together enough money to fly to Dubai, United Arab Emirates, where they could apply for U.S. visas. They were interviewed about their interest in visiting the United States, and they showed the consulate their demo album.

"We were searched four times, but everybody was really nice," Mohebbi said.

Eventually their visas were approved, but it was two weeks after the music festival ended March 20. They weren't angry, just disappointed.

"It's part of the 'Axis of Evil' problem," Mohebbi said, pausing midway through a practice session one recent night. "We're not politicians, we're musicians."

Like his idol Dylan, Mohebbi likes to say his music is only political to those who hear politics in it. In "New Sky," he sings that "the new sky's falling, the new sky's falling, the new sky's falling on me."

He gets a lot of questions about that one.

"Some people might say 'New Sky' is about political change, but maybe it's not. I mean, it's just words and music that happen to go together," he said.

It's a glib answer and he knows it. But after all, he says, in Iran "you never know what's going to cause problems."

Like anything that dances on the borders of taboos in Iran today, being a musician makes you a bit older and more cynical than your age. That applies to pianist Sardar Sarmast, trombone player Slamak Khaledi, bassist Alireza Pourassad, drummer Yayha Alkhansa and sitar player Shervin Shahamipour -- none of whom is over 27. They would rather skip the interviews and just play music, but they know the interviews might help them make the case to be able to play at all.

Only occasionally do they betray a hint of the frustration that besets their lives. Mohebbi wrote "My Sweet Little Terrorist Song," after the first allegations of abuse at Guantanamo Bay emerged.

"I just wanna watch Dylan playin' live, I won't fly into the Pentagon alive," he sings.

It's a sad, clever song about being young and Muslim, about wanting to visit Paris and California, about living in "the Axis of Evil."

In June, 127 got some good news. They were awaiting word on another visa request -- they are invited to the Arezzo Wave Love Festival in Italy. This time, the visa came through in time.

Members of 127 practice in cramped quarters. Invited to the South by Southwest festival this year, their visas were issued too late.