It's understood that the review is a matter of course as the telco's three-year contract with incumbent agencies NagaDDB and TBWA (which manages the company's youth portfolio) is coming to an end.
Other agencies involved in the pitch are McCann Worldgroup, Grey and Havas Worldwide.
The agencies will be submitting their proposals early next week with presentations to be held on the 25 July.
NagaDDB and DiGi go back 16 years. The agency is behind the creation of the telco's iconic mascot, the Yellow Coverage Fellow, which was introduced at the end of 2006 to promote DiGi's increased network coverage.