Some CI╔ board members might have asked more questions about the Esat deal if the company had not so desperately needed the cash it promised.
Government-appointed board member, Ms Tras Honan, told the inquiry she "regretted deeply" that she did not try to get more information.
"But the whole thing was clouded. The big thing was that we had our back to the wall financially," she said.
Worker-elected director, Mr Michael Faherty, said he backed the board's decision to approve heads of agreement for the deal despite none of the board members having expertise in telecommunications and no detailed questions being asked until much later.
He said the chairman told the board CI╔ would get £2 million annually at a time when the company was "in a bad way" financially.
"There was a culture of getting involved in anything that would bring in an income stream. On the basis of that, most people would have thought this would be a good idea."
Fellow worker-director, Mr Paul Cullen, said he was relying on the people doing the deal to pro vide the expert advice as he knew nothing about the technology.
"At that time, in hindsight, we did not get enough information," he said.
All three told the inquiry they knew nothing of a consultant's paper which raised reservations about Esat as a venture partner for CI╔ while backing an alternative British Telecom project as "risk-free".
Mr Faherty said he recalled being told of two other proposals besides Esat's but he saw nothing in writing about them and he believed they were non- runners.
Mr P.J. Lynch, a former director of CI╔ and now chairman of Modern Networks Ltd, one of the rail signalling project contractors, also said he had not seen the consultant's paper.
But he argued that the Esat deal was also risk-free because it was laying its phone cables at no cost to CI╔.
Mr Lynch rejected a suggestion from Mr Pat Rabbitte TD that his decision to join MNL after he resigned from CI╔ in November 1998 - a move also made by four CI╔ employees involved in the negotiation of MNL's contract - may have created a perception that was problematic for the company.
"I don't see a problem. I am deeply disturbed at the innuendo," he said.
The inquiry is investigating whether the Esat deal hampered CI╔'s mini-CTC signalling project which is now two years overdue and £36 million over budget.