LONDON (Reuters) - BT (>> BT Group plc), Britain's biggest telecoms group, vowed to improve customer service for its millions of residential consumers and the other telecoms companies that rely on its network after widespread criticism.

Chief Executive Gavin Patterson said the company had been taken aback by the criticism it received in a regulatory review of the industry which focused on BT's Openreach unit that runs the national broadband network.

"Around the DCR (Digital Communications Review), I think it is fair to say we underestimated the degree of criticism in our service and in our levels of investment, this has eroded trust in our brand," he said at the Deloitte and Enders Analysis Media & Telecoms conference on Thursday.

BT has endured a rough ride in recent months, battling with the regulator Ofcom over how it should run the Openreach unit, cutting its profit forecast due to a downturn in British public sector work and discovering fraud in Italy.

Patterson said the company had listened to the criticism and was open to taking on board the interests of its Openreach customers when deciding how much to invest. He added that he hoped to be able to agree a settlement with Ofcom on the issue.

"When it comes to our (consumer and business) customers, let me be absolutely clear, our service must get better," he said.

BT's rivals, including Sky (>> SKY PLC), TalkTalk (>> Talktalk Telecom Group PLC) and Vodafone (>> Vodafone Group plc), say Openreach delivers poor service, does not invest enough in the network and is run to serve BT's bottom line rather than the interests of Britain's broadband needs.

Ofcom Chief Executive Sharon White, speaking on the sidelines of the conference, said BT could "settle tomorrow" the long-running dispute if it agreed to the regulator's demand to make Openreach completely separate, legally as well as operationally, from the rest of the group.

Ofcom believes reform would spur investment in the ageing network and has said it will go to the European Commission to try to force its plan, but White added that "the door was always open with BT".

Patterson, who has turned BT into a more powerful competitor by acquiring mobile operator EE and snapping up TV sports rights, said the downturn in recent months had been "humbling" for all at BT.

He reinvigorated BT by taking on rival Sky in the sports rights market, paying 897 million pounds for a three-year deal for Champions League soccer rights.

The two will go head-to-head again in the coming weeks when they bid again for those rights, which could see another jump in the price paid. Patterson, however, said rampant inflation in sports rights would eventually ease.

"We have made it very clear we do not need to be number one in the sport market, but we need to be a viable number two," he said. "If you look at the sports market itself, it is pretty saturated in terms of users and consumption today, so I hope at some point in the future we can find a more stable equilibrium."

(Editing by Kate Holton and Elaine Hardcastle)

By Paul Sandle