BT's offering 50 per cent more Openzone WiFi hotspot minutes - but the offer is about as limited as it can be.

It applies only to its £6 one-hour voucher, which now offers 90 non-consecutive minutes if used within 24 hours. There's no corresponding offer for the longer-term vouchers, such as the 24-hour or 30-day products. And the offer runs out on 31 January 2007.

Despite the fact that BT offers a range of price plans, there's also still no way for a user with moderate but sporadic usage patterns to avoid either paying for large amounts of time they never use because the vouchers all have tight expiry dates, or having to pay per minute, which is hugely expensive. This scheme costs 20 times more for each minute than a 30-day voucher - which expires after one month.

Compare this to T-Mobile's subscription plan which offers unlimited minutes for £20 per month, which includes 300 Openzone minutes - BT's best effort is £25 per month for 4,000 minutes - and BT's price plans still look poor value.

That's especially true compared to remote access provider Sirocom, which has been forced to provide WiFi access for nothing as customers are reluctant to pay for it. The Sirocom bundles include a pool of hours per month, to be used by any user within the customer company. After six months, WiFi will no longer be free, said business development manager Barrie Desmond: "But monthly fees won't go up by more than 20 percent. It's not like getting people hooked on heroin."