The review, which kicked off in October, is in the final stages, with BT expected to make a decision before the end of the year. Incumbents Zed and Starcom are still in the running, under the Publicis banner, as is WPP's GroupM, led by Mediaedge:cia. Omnicom declined to confirm that it was in or out of the running.
It is said that the comprehensive review process, which covers planning and buying for both on and offline media, has involved a series of negotiations and price submissions, but has been devoid of the usual agency service pitches.
Agencies have been asked to submit specific quotes for the various components of the account, the insider said, which suggests that BT is looking to agree the lowest possible prices across the board. It is understood the review is being led by BT's finance director.
"It sounds like an auction, and that says a lot about the way the business has got to in terms of its marketing," another source told Media Week.
However, another agency head played down the procurement aspect of the review. He said: "Any pitch goes through a process where the competing agencies have to show they are supplying value. In this case, procurement is looking to get the best deal, but that's not massively different to the normal process."
Mediaedge:cia took on BT's media planning in August, previously handled in-house.
Starcom's relationship with BT goes back five years to when it captured the press buying business; two years ago, it won the TV buying account from The Allmond Partnership. Zed Media won the £15m online business in 2005.
BT declined to comment.