The visit to the Win Back centre in Glasgow, at the invitation of BT, follows further allegations by cable companies that BT has been calling ex-directory cable customers, in breach of the Telecommunications Act.
As revealed by the Independent yesterday, a further seven complaints have been forwarded by cable operators to Oftel, of which five were passed on yesterday to BT.
The telecoms giant is expected to respond to the latest charges by the end of today, and Oftel is expected to make a formal statement early next week.
The allegations concern what the cable operators believe is an illegal campaign to staunch the loss of BT customers to cable, involving the direct tele-marketing of ex-directory cable phone customers.
Cable operators have privately rejected BT's initial explanation that a "computer glitch" was at fault.
Bob Frost, chief executive of the Cable Communications Association, said last night: "We're extremely concerned about further reports that we are recieving and are anxious to hear the reply that we are going to get from BT."
A BT spokesman continued to claim last night that "all confidential information that BT has is held in a separate data base. Our marketers do not have access to that."
He added that there had been no evidence the "wall had been breeched".