Last week, London's Earl's Court conference centre and the Heathrow Hilton Hotel at Heathrow Airport became the first sites to offer the service.
One hundred employees of Motorola's UK division will be early users of the service; the company is helping BT to set up.
One of the network hosts was enthusiastic about the potential of the technology.
"The Wi-Fi service is going to change business travel," said a Hilton spokesman. Hilton operates 499 hotels worldwide and plans to expand the WLAN service, which uses the Wi-Fi or IEEE 802.11b protocol, to all of its airport hotels as soon as it can.
The Hilton does not know how many people are using the free service to hook up their laptops to the Internet or how those users are finding the experience.
"BT is in charge of the trials and we'll be briefed just before 1 August on how the trials went," the spokesman said.
Motorola, meanwhile, is still setting up the system with BT and Cisco Systems, and its 100 employees have yet to begin using the service.
BT plans to have 400 wireless LAN access points in operation in places such as airports, hotels, conference centres, train stations and coffee shops by next June.
For the 1 August launch, BT expects to have 20 access points available, with a further 50 being rolled out by December.
The service will cost around £95 a month for a fixed number of hours, which BT has yet to fix, or 10p per minute.
To encourage early adoption, BT is promising a 50% discount for monthly users who sign up before the end of the year.