Police were forced to use their own mobile phones during the August riots after a multi-billion pound radio system collapsed, according to a leaked internal report on how UK forces responded to the disorder.
The Police Federation Review revealed that the failings of the digital Airwave radio network used by the Metropolitan Police was one of the reasons why the capital's officers were "always approximately half-an-hour behind the rioters", it was reported.
This is partly why officers kept arriving at areas where the disorder had moved on from, the document, which was leaked to The Observer, said.
It adds: "Officers on the ground and in command resorted, in the majority, to the use of mobile phones to co-ordinate a response."
The internal review also reveals that after the trouble erupted, "forces often did not know how may officers they had on or off shift" and senior officers took charge in some places "often without the local knowledge of the areas", making it easier to be outmanoeuvred by rioters.
It also concluded that severe equipment shortages among officers meant they were unable to be mobilised in a public order capacity.
"Mutual aid officers were often dispatched without enough equipment. They therefore could not be mobilised in a public order capacity as all the riot gear was in use," the investigation compiled by the federation's operational policing sub-committee, found.
Scotland Yard last week released an interim report into the riots which found there were not enough officers to deal with the unprecedented scale and spread of the disorder.
Chiefs also said intelligence gathering "could not cope with the scale and speed of the spread of disorder".