Taji, Iraq (CNN) -- Under a sweltering sun, Fallah al Araiby hunched over the hood of a car, scrubbing away the dirt.
Once, his son used to work alongside him on a busy street corner in central Baghdad. Now, he does it alone.
His son is one of the thousands who have answered the call from Iraq's top Shiite cleric to take up arms to protect Iraq from extremist Sunni fighters whose aim is to oust Prime Minister Nuri al-Maliki's Shiite-dominated government and establish an Islamic state that stretches from Iraq to northern Syria.
With three days of training, his son -- 25-year-old Ali -- was given a helmet, a rifle, a magazine of ammunition and sent to the front line, al Araiby said.
Some 23,000 volunteers, according to Col. Shihab Hamoud Nasir, have signed up for the security forces since ISIS seized Iraq's second-largest city, Mosul. In a lightning advance, ISIS seize large swaths of northern and western Iraq earlier this month.
Al Araiby's son and many like him were taken by the loads in buses and trucks to the sprawling Taji training base, 20 miles (32 kilometers) north of Baghdad. There, under a makeshift canopy, volunteers wait for their turn to begin training.
When they are called, they are put into formation where they march -- sometimes out of step -- and practice shooting.
They get about a week to 10 days of training, Nasir said.
Much has been made about whether it's enough training to take on the seasoned ISIS fighters, who have had significant success in battling Syrian President Bashar al-Assad's forces.
ISIS fighters and allied Sunni militants have launched a number of attacks against military bases and checkpoints, killing a large number of the new recruits. Iraq's military spokesman, Maj. Gen. Qassim Atta, details the deaths of ISIS fighters during military briefings televised near daily, but he says almost nothing about Iraqi security force casualties.
But sporadic reports about the fighting from police and local government officials paint a sometimes bleak picture. Take the report about fighting at a military base south of Baghdad:
ISIS fighters launched an attack Sunday against the base at Jurf al-Sakhar, on the outskirts of Hilla, where an infantry brigade is based.
At least seven soldiers, all new recruits, were killed and 15 were wounded, according to police officials.
It was the second such attack on the base in as many days.
Still, volunteers come by the hundreds to Taji to train.
"I can assure you that volunteers came from all of Iraq's provinces, and a few were underage but we convinced them to change their decision and return to their families," Nasir said.
While Nasir said recruits are not asked about their religious affiliation, the majority are Shiite who answered the call put forward by Ayatollah Ali al-Sistani, the country's top Shiite cleric.
Among them is 23-year-old Mohammed Jassim, who left his job as a taxi driver in Baghdad's Sadr City to take up arms.
"This is my first day here, and I am ready to be deployed to the field, even to the front line, if that's needed," he said as he sat on a wooden bench waiting to be called.
As Nasir detailed the training for CNN, he was interrupted by a man in his 70s who reminded him that he has come to the training center every day for much of the last two weeks.
"When will it be my turn," he asks Nasir. "When God wills," the colonel tells him. "When God wills."
On the street corner in Baghdad, al Araiby praises his son's decision to volunteer. He doesn't know where he's been deployed.
"No, I am not afraid for him. He is a brave young man, and it is his duty to obey the religious authority," he said.
"... I encouraged my son to join as a volunteer because this is our responsibility and duty."
The 50-year-old al Araiby hopes to join his son at the front line. He says he's just waiting for the military to call.