OgilvyOne has worked with BT on its direct marketing since 2001.
Chemistry has held EE’s direct marketing business since 2012, having previously handled the direct marketing for its predecessor Orange.
In 2014, EE cut marketing spend and moved its business-to-business account from Chemistry to McCann Enterprise.
The direct marketing review comes after BT finalised the line-up for its £160m consolidated media account, in which incumbent agencies Maxus (BT) and MEC (EE) were retained. The Group M shops are setting up a bespoke unit called Team Connect to service the account.
Abbott Mead Vickers BBDO handles BT’s above-the-line work, while Saatchi & Saatchi is the retained creative agency for EE.
BT completed its takeover of EE in January. While the telecoms giant has chosen to retain the EE brand, it has said it expects to make cost savings of £400m a year.
BT and OgilvyOne picked up silver and bronze at last year’s DMA Awards for "We were going to email but…" and "Pub signs" for BT Sport.
BT declined to comment on the direct process or whether it would review advertising next.