Steve Andrews, BT Group chief of mobility and convergence, said Friday that the offer was one part of the company's drive to strengthen its virtual mobile operations.
"Anyone who buys BT mobile will get very significantly lower prices on our Wi-Fi," Andrews said.
An official announcement is expected in the next couple of weeks.
BT spun off its mobile operations in 2002 when BT Cellnet became O2, and was floated on the stock market. BT still hopes to be a major player in the mobile space, and on Friday it launched a new range of mobile business services based on Vodafone's mobile network.
This includes a service called the mobile Virtual Private Network. BT said the service will mean lower mobile bills for companies because it "enables an employee's mobile device to become an extension of the switchboard."
BT already offered some mobile services through a tie-in with O2, but Friday's deal with Vodafone replaced this agreement. It hopes to be generating 1 billion pounds ($1.86 billion) a year from "mobility and convergence revenue" within five years.
BT also is making plans to launch a Wi-Fi phone. Andrews said he expected trial models of a BT Wi-Fi device for corporate customers to appear "within the window of the next 12 months." He suggested that commercial deployment could be 18 months away.
Such a device would be a second-generation Bluephone--BT's converged mobile device that is due to launch next year.
Andrews added that there are several problems to be overcome by manufacturers, such as battery life, before Wi-Fi phones are ready for mass-market deployment.
Graeme Wearden of ZDNet UK reported from London.