Vodafone has called an estimated $523 million global media planning and buying review, less than a year after bringing its biddable media in-house.
The British telecoms giant operates in 25 markets and the account covers all of its media buying that has not been insourced.
The review will focus on established media such as TV, radio, out-of-home, news and magazine brands, and some elements of digital, plus media evaluation and partnerships.
Vodafone is looking to appoint one agency group and has invited WPP, the incumbent, and other holding companies to pitch.
Key markets include Australia, Germany, India, South Africa, Spain and the UK.
MEC, now Wavemaker, has held the business since 2014, after beating Dentsu Aegis Network’s Carat and Omnicom’s OMD in a pitch.
Vodafone first consolidated its media buying into one group in 2009, when OMD won the account.
A source close to Vodafone indicated that it is a planned, periodic review after five years, rather than a decision that was driven by its in-housing initiative.
The FTSE-100 telecoms company does not disclose its media budget but is estimated to spend up to £600 million (US$784 million) a year.
It is thought that the in-house team manages about a third of Vodafone's media in biddable channels such as search, social and programmatic. That would mean an external agency is likely to manage in the region of £400 million (US$523 million) on behalf of the brand.
Vodafone brought most of its digital media buying in-house in June last year in a move that sent shockwaves across the agency sector because of the scale of the project, meaning a reduction in Wavemaker’s scope.
Sara Martins de Oliveira, global director of brand and media at Vodafone, told Campaign in an interview last month that the early results from 12 in-sourced campaigns were "overwhelmingly good".
In-housing was on course to be between 10% and 15% "more effective" in the first year, with about 70% of the improved effectiveness coming from "media efficiencies" and 30% from savings, Oliveira said.
Vodafone launched in-house teams in 11 markets and recruited 120 out of the 150 people required in the first nine months.
It has continued the process of in-sourcing since then, according to the source close to the company.
In her interview in March, Oliveira said: "My biggest frustration right now is the creative."
She explained: "Where is my really digital creative, optimised, at scale, done in an agile, very fast way? I don’t have an answer yet from an agency."
Oliveira is overseeing the media review. Vodafone has a broad relationship with WPP, which includes creative and CRM, as well as media.
Other telecoms groups, including Sprint and T-Mobile in the US, have been bringing aspects of digital media buying in-house to improve efficiencies and make better use of data.
Some observers believe in-house teams will struggle to recruit and retain talent and keep up with best practice.
Oliveira has said Vodafone has not faced any "huge" challenges on media insourcing so far.