Karen Harrison, the head of brand and communications at the mobile operator, has contacted a number of agencies about a review, which she is planning to kick off next month. It is not clear whether either of the incumbents on the account will repitch.
Glue has worked on various advertising campaigns for T-Mobile. In October 2005, it launched T-Mobile TV, which allowed users to make spoof news bulletins featuring mobile footage of friends.
In August, it created a mobile and digital campaign to promote Street Gigs, T-Mobile's live music events.
Agency.com has worked with T-Mobile since 1998, when it designed the original T-Mobile global website. It has since worked on website design and campaigns in The Netherlands and also on redesigning the mobile operator's corporate website.
A spokeswoman for T-Mobile said: "We regularly keep in touch with agencies to gather information on the market but this does not necessarily mean that we are pitching the business."