It took about thirty minutes to find an answer. Robed tech adepts poked and prodded at arcane equipment and incanted litanies of consecration to the Machine God as the manipulated one of the vox stations with their mechadendrites. General Hetad gave up grumbling that it was a waste of time after the first couple of venomous looks from the Governor. 

"We have something," the lead techpriest, declared, his voice a synthetic buzz from the speaker which replaced his mouth. Like many of the Mechanicus he was heavily augmented, lumps and bumps beneath his red robes testament to further augmentation beneath. Like most Valhallan's Katiya had a slight revulstion for the practice of replacing flesh with mechanical replacements. Many officers and troops in the Imperial Guard used augments to repair battle damage of course, but the Cult of Mechanicus seemed to revel in voluntarily augmentation.

"What is it?" the Governor demanded impatiently. The techpriest touched a control and crackling audio sprang into life.

"Three, seven, fourteen, twenty one, six..." a monotone female voice intoned. It began to repeat after twenty numbers, clearly playing on a loop.

"This is the only unauthorized vox traffic we have been able to detect," the tech-priest reported.

"But this is just numbers, obviously its not important," General Hetard blustered.

"No doubt Corporal Vomer, is very brave but his..." the general continued. The Governor silenced him with a wave of her hand.

"It's Connors," she corrected idly though her mind was clearly focused on the transmission.

"It is a numbers station," Katiya declared, drawing all eyes to her.

"A what?" the Governor demanded, eyes bright and intent.

"Its an automated broadcast of coded instructions, the numbers correspond to a certain course of action," she explained.

"Can you tell us when this began?" Katiya asked the tech priest.

"Seventeen hundred hours thirty seven minutes and sixteen seconds local time," the tech priests mechanical voice droned.

"Just before the Arbities building was bombed," Katiya mused. That wasn't alot of time to mobilize the kind of crowd that was in the streets. Not unless they had been preped in advance anyway.

"Where is it transmitting from?" the Governor asked.

"There is an eighty six percent match to a disused PDF vox station in the hills north of the city," the tech priest supplied.