Islamabad (CNN) -- Cell phones were silent in Islamabad on Monday, but thousands of demonstrators heading there soon planned to be heard loud and clear. Pakistan's government shut down all cell service as part of a strict security crackdown as cleric Tahir ul Qadri's "Million Man March" convoy headed toward the capital. Qadri is a well-known Muslim cleric who has returned home and promised a Pakistani equivalent of Egypt's Tahrir Square protests. Much of Pakistan watched in anticipation as thousands of people, led by Qadri, headed toward Islamabad with police and soldiers lining the rally route. They are expected to join more than a thousand protesters who arrived earlier in the day as part of a demonstration calling for reforms to clean up national politics, long criticized as corrupt, ahead of elections this year. "We want change in the establishment and we want to save our country," said a man who sold his bicycle so he could afford to attend the rally, according to CNN affiliate GEO TV. Qadri returned to Pakistan last month after living in Canada for eight years. He is waging an aggressive campaign against the political elite. Local television showed a convoy of buses, vans and cars proceeding to the capital. Participants packed the vehicles, many waving the national flag. Qadri traveled by bulletproof van. Some joined the procession on foot. Some demonstrators from the eastern city of Lahore reached Kharian, halfway to their destination. The next point would be the city of Rawalpindi, on the outskirts of Islamabad. Dubbed by organizers the "Million Man March," the convoy was expected to pick up more people as it moved through different towns. Exact figures were unclear, but witnesses estimated around 20,000 people had participated so far. Pakistani Interior Minister Rehman Malik, who visited some rally sites via helicopter Monday, said the low turnout meant that Qadri's event had "badly failed." Authorities in Islamabad erected barricades from large containers, vehicles and barbed wire on certain streets to channel the anticipated crowd and prevent protesters from getting too close to the national Parliament, the stated focal point of the demonstration. Police have also said they don't want the protesters to pass through Rawalpindi. Malik said the government was aware of threats to attack Qadri and some of his close associates, and five militants who said their group would target the cleric had been arrested in Karachi. The interior minister has been concerned about the potentially provocative march for a while. "The residents of Islamabad are scared that mobs will raid their houses and there will be violence and murder," Malik said last week. Some demonstrators beat Qadri's convoy to an area dubbed the "blue zone," near Parliament and the presidential home, and played patriotic songs and raised flags. We want change. We want change," they chanted. One man in a male-only area told GEO TV viewers watching at home that change does not occur while sitting down. "We all must rally and come together for change, and a better future and stronger Pakistan," he said. One female protester, rallying in the space provided for women and children, was prepared for a long demonstration. We have come here with our bedding and food supplies, so that if we need to stay here, we are prepared to do so. We will stay here for as long as it takes to change the present situation in Pakistan," she told GEO TV. The rapid rise of Qadri's movement -- his thousands of supporters and heavy media campaign -- has raised questions about the source of his resources. He has called for a caretaker administration to replace the current government and carry out election reforms ahead of an upcoming vote. His suggestion that the judiciary and the military weigh in on the composition of the interim government has raised concerns in a country where military leaders have repeatedly seized power and ruled for long periods of time. He denies allegations that he is a military puppet and maintains that he is simply seeking to ensure a corruption-free electoral process. Supporters say that Qadri aims to make positive change. Corruption is widely considered to be a chronic problem in Pakistan's political system, and President Asif Ali Zardari has spent time in prison on corruption charges. His campaign comes more than a year after anti-corruption demonstrator Anna Hazare roiled Indian politics with a hunger strike that called for the introduction of strong anti-graft measures. That occurred during his time in Canada when he spoke out in videos and books. CNN's Aliza Kassin, Saima Mohsin and Nasir Habib also contributed to this report. Mark Morgenstein updated it in Atlanta.