It is likely to be one of the biggest media reviews of the year in the UK as BT is Britain’s third biggest advertiser behind arch-rival Sky and Procter & Gamble.
BT is believed to be at the early stages of the review and is looking for cost-savings, following the completion of its takeover of EE in January.
Maxus handles BT, worth upwards of £100m a year, and MEC looks after EE, worth in the region of £60m, at present. Both agencies are part of WPP’s Group M.
Sources said BT may be considering a number of options and is not certain to consolidate its media-buying with a single agency. It is understood that BT has approached other agency groups apart from Group M.
BT said: "We do not comment on rumour and speculation."
Several senior figures have left EE following the acquisition by BT, including Pippa Dunn, the former chief marketing officer, and Spencer McHugh, who was her number two and is leaving next month after 16 years having joined when it was Orange. Orange owner France-Telecom merged with T-Mobile to form EE in 2009.
Earlier this month, Alec Baldwin fronted BT's latest ad in its "behind the scenes" campaign, which features Hollywood stars gently mocking themselves while promoting the brand's internet and 4G speeds.