* Rebels scan into army frequencies
* Call on Syrian "brothers" to turn against Assad
* Rebels sure many soldiers are wavering
By Erika Solomon and Douglas Hamilton
BEIRUT, April 4 (Reuters) - Between bursts of machinegun and mortar fire, Syrian rebels switch their struggle against President Bashar al-Assad to their radio sets, tuning in on army frequencies to urge the soldiers fighting them to desert.
"If you want to be a good person, you will defect from that army. You should come over here and serve your people. Don't insult your dignity like this. I saw Assad's oppression, I saw grief and injustice with you guys," says a rebel voice.
The crackly appeal is on a YouTube video showing scruffy fighters of the Free Syrian Army who have just taken cover in an alleyway in the central city of Homs. They are hovering around a commander fiddling with the tuner knob of a walkie-talkie.
There's a strange hush as they strain to listen in.
"We are fighting to the death in the name of God almighty. We fight because of a belief, not a man who is no better than me or you," says the rebel voice. "Bashar is fighting to keep his throne and letting us kill each other."
Most YouTube videos cannot be verified conclusively.
The shaky, grainy amateur clips that have kept Syria's bloody conflict in the world's eyes for over a year are mostly sound-tracks of bangs and flashes punctuated by rebel yells of "Allahu Akbar" (God is great).
But some include audible dialogue as rebels - many of them army deserters themselves - implore their former brothers-in-arms to defect and join the fight against 40 years of Assad family rule.
"Sometimes rebels try to scare the army, sometimes they mock them or eavesdrop on them. Or they call on soldiers to join them," a rebel whose nom de guerre is Abu Thaer told Reuters.
"They are always searching on their walkie-talkies. It's hard to catch the frequency, but when we do we make the best use of it," he said by telephone from an undisclosed location.
"YOU ARE OUR BROTHERS"
Syria's uprising started with peaceful protests but turned into urban warfare after many soldiers and officers changed sides, disgusted at orders to shoot unarmed demonstrators.
In the past two months, the army appears to have gained the advantage, routing rebels from most of their strongholds across Syria such as the Baba Amr district of Homs, where a smiling Assad made what looked like a victory visit last week.
Insurgents now rely mostly on hit-and-run tactics. Western powers who want Assad to go say they have no plans to arm his foes, but they are providing "non-lethal aid", which includes communications gear such as walkie-talkies.
Samir al-Kurdi, an army deserter with anti-Assad forces in Homs, heart of the insurgency, said the rebels keep reaching out because they are convinced many soldiers in the 300,000-strong army want to defect to their force of some 15,000.
Often they get no response, he said. "They don't say a thing, they don't really try to talk to us on the radios." The penalty for desertion is death, rebels say.
Syrian forces have killed more than 9,000 people in the crackdown on unrest, according to the United Nations. The government, which says it is fighting foreign-backed terrorists, estimates that fighters have killed more than 3,000 of its men.
"If we can, during or after an operation, we'll call out to them on loud-hailers. We'll promise to protect them," Kurdi says.
In one YouTube video shot during another battle in Homs, anti-Assad forces have blown up two tanks which are blazing in the darkness. They are cheering. One fighter starts shouting to unseen troops at the other end of the street.
The light of the flames makes silhouettes of soldiers crouching in nearby buildings.
"Oh soldiers, recruits, I was one of you. I am a brother. I was in the 4th Division ... Come to us. We promise your safety. You are our brothers. Your family is waiting for you," he shouts. "What good has Bashar ever done for you?"
Then there's a burst of cheering and laughter as he shouts to his own men, raising their guns in front of the fire: "Hey, Free Army, will we promise them safety or will we not?"
"Yes, yes," they chorus. But no one steps out from the darkness.
Sometimes the combatants in a walkie-talkie exchange even seem to know each other - which is not impossible in a war that has divided city neighbourhoods and even streets along political, sectarian and religious lines.
In the Homs video, the rebel voice on the walkie-talkie calls an army commander by the nickname "Abu Odai".
"They are saying this is a fight to the death. A fight to the death means you'll find our dead bodies rigged with bombs, Do you understand me? Abu Odai, Abu Odai, what will you do?" the rebel asks.
"This conversation is over," the unseen officer replies. (Editing by Alistair Lyon)