A computer glitch is blamed for leaving BT's ADSL customers stranded this week, raising questions about the quality of its broadband offering. The glitch -- in which IP addresses are wrongly allocated -- has left users with what BT describes as an "intermittent service". BT admits that "everyone" using its consumer ADSL package could be affected but is unable to say how many users have been affected. A spokesman claims its engineers are working around the clock to solve the problem. The telco giant reassures users it is only a temporary glitch. "The service doesn't need to be rebuilt," says a BT spokesman. Claims for compensation will be dealt with on an individual basis, he says. In the business arena BT is also playing its ADSL offering cautiously and currently offers no guarantee of service levels. According to the BT spokesman this is standard practise with new technologies. "People underestimate the complexity of setting up an ADSL service," he says. For business ISP Mistral -- which launched its corporate ADSL offering Tuesday -- the lack of service level agreements is a serious issue. It buys ADSL wholesale from BT and would like to guarantee its customers a certain standard of service. "In a business environment you do need service level agreements but because BT is the only company offering it there is no pressure on them to provide them," says Mistral's director Steve Spink. In fact the ISP is fed up with being tied to BT's wholesale service. "We spend too much time talking to BT and we will certainly shop around when the local loop is unbundled," Spink says. It is not the first time questions have been raised about the robustness of ADSL. Experts are keen to point out its limitations, one of the biggest issues being the fact it doesn't work if customers are over four kilometres from an exchange. Analyst with research firm Ovum Tim Johnson believes BT is not offering service guarantees because "it is not sure it can guarantee it". He believes BT has another policy towards ADSL. "It is a case of never mind the quality, feel the width," says Johnson. To have your say online click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.