The day ultraconservative Mahmoud Ahmadinejad was elected to the presidency last June, an Iranian rock band received a phone call.
A nervous Interior Ministry official was on the line. An concert scheduled to take place at the ministry - sanctuary of powerful security and intelligence agencies - would have to be called off, he said, because "we can't guarantee your security."
Stunned, the rockers thought they were witnessing the start of a long-expected clampdown against social restrictions that had eased during the era of President Mohammad Khatami.
But that appears to have been a false alarm, band-members say - for now. "Very little has changed so far," says guitarist Amir Tehrani. "We are expecting it, but it hasn't come. Yet."
In fact, three months after Mr. Ahmadinejad's victory, Iranians have seen relatively few signs of a rollback of the increased tolerance in recent years of everything from more form-fitting women's attire to rock 'n' roll.
But tough and capricious rules are still in force. And as interest in music of all types deepens across Iran - and as Tehran marked International Music Day on Saturday - musicians of all styles say the country is entering a critical phase that will define the future of musical performance here.
Capping the day with a concert of traditional and avant-garde music in Tehran's plush Vahdat Hall, they say the time has come to clarify the new government's position.
"The music we are performing now is a [test] to find out how they will react, how the new government is thinking," says Kambiz Roshanraven, director of the House of Music in Tehran, an independent umbrella group for musicians he founded six years ago. "I'm not sure what will happen after Music Day, but I think the House of Music will continue proudly as a center for music."
Uncertainty has troubled the music scene since the 1979 Islamic Revolution forced musicians to hide their instruments. It took an edict from Ayatollah Ruhollah Khomeini, leader of the revolution, to convince some that it was safe to begin playing again - though martial music to boost war efforts against Iraq in the 1980s was officially preferred, and harsh restrictions applied.
Until a few years ago, only live performances of traditional music were allowed. While male singing is now permitted, female vocals are not. It remains illegal for TV to show instruments - which required a special permit even to transport, for a time in 1996. But today, every other car seems to have a young driver at the wheel, blasting ear-shattering and sometimes lewd Western rock 'n' roll tunes.
At a concert capping International Day performances Saturday, veteran conductor and composer Alireza Mashayekhi asked for reassurance from the podium.
"Please clarify the position of music one time - just once! - so we know what to do about it," he asked, before conducting one of his own powerfully rhythmic, unconventional works for percussion and piano.
"If you don't have knowledge of [music], then don't make any comment," added Mr. Mashayekhi, decrying political control of musical life. There were no turbans in the audience, denoting an absent of clerics, but several men wore once-forbidden Western ties.
"One person works months and months on this piece, and how can you say immediately this is 'good' or 'bad'?" asked Mashayekhi of critics. "You can say you like it, or not, but don't make a scientific analysis of it."
Underground heavy metal bands long played in hidden rooms, finally winning the fight in recent years to play publicly, though approved venues include small hospital auditoriums and the Interior Ministry.
Bass guitar player Babak Riahipour, renowned in Iran and now developing a band that sings in English, says the number of his students has grown to 40 from four. A planned concert of his at a horse track last week was canceled.
The House of Music, which represents 7,000 musicians and has a waiting list of 400 more, says there are now 1,000 instrument makers in Iran. Before the revolution, there were a dozen music schools. That number has multiplied to 600 in the capital alone, and 600 more nationally.
"It's unbelievable," says director Roshanraven, who says he expects to meet in the coming days with new officials of the Ministry of Culture and Islamic Guidance to lobby for greater openness.
"We can't find a time when music has been so widely played in Iran," says Roshanraven, who earned his PhD in composition at the University of Southern California long ago. "We are trying to find out what makes a concert be canceled. We have to do something about it - we must protect these groups."
Different rules apply to traditional and pop groups. A dozen or so foreign ensembles visit each year, including a French group that played Western classical music last week.
At the Fajr music festival in Tehran each February, musicians play 20 venues for 20 days. "We have intelligent, talented musicians, but without enough [government] support," says Mehdi Siadat, who plays the santur, or dulcimer, in the traditional group Javan, or "Young."
"We always have [fear of greater restrictions]," says Mr. Siadat. "The government promises more and more. I'm an optimist, but...."
Few are predicting new opening by Ahmadinejad, who has filled key security slots with men with hard-line, basij backgrounds. Their commitment to letting Iranians play and hear what they want is unclear.
"Maybe it will be better, because Iranians are young people, and young people like pop and classical," says Mohammad Ali Kianinejad, director of Javan. He notes that symphonic concerts - including one last week for Beethoven afficianados - are in great demand. "They played six nights here and were all sold out, so how can that be stopped?"