OMD, which handles the company's offline media planning and buying, and BLM Quantum, the incumbent on the online media account, are expected to be invited to repitch for the business alongside non-roster agencies.
It is understood 118 118 aims to consolidate the entire business into one shop.
BLM Quantum, the specialist digital arm of Arena BLM, won 118 118's online media account in October last year from OMD.
The agency was appointed after presenting to 118 118 on a strategy to promote its services through digital channels.
The operator of 118 118, The Number, had initially kicked off a pitch for a digital creative agency, but chose instead to appoint BLM Quantum to focus on a media-led strategy for online.
At the end of last month, 118 118 awarded a global ad brief to The Brooklyn Brothers. WCRS, the incumbent on the account, remains on the company's roster.
Last week, The Brooklyn Brothers launched a new ad campaign featuring Ray ?Parker Jr singing a version of his classic Ghostbusters song.
Separately, 118 118 has ended its digital advertising review by handing two agencies the chance to work on a paid-for brief.
Work Club and LBi beat Tequila and Dare to be given the opportunity to work with the brand further.
A spokesman for Oystercatchers, which handled the pitch, said: "118 118 saw two really interesting ideas and wanted to give the agencies a chance to develop them further while rewarding them for their effort."
The agencies will now have a month to develop their ideas on how to improve the brand's digital offering.