River is understood to be one of several agencies competing for the brief, via a competitive pitch, with an announcement expected within the next month.
Hotline is a quarterly magazine, available free on Virgin Trains, which features a mix of celebrity columnists and mainstream writers, along with articles featuring journeys on the Virgin Trains network.
The magazine is around eight years old, and registered an ABC figure of 124,740 between July and December 2007.
Hotline, which is part ad-funded and part fee-based, dedicates some editorial to green issues and is printed on 100% recycled paper.
The pitch is being overseen by Virgin Trains procurement manager Adam Pitt.
River Publishing, which has held the Virgin Trains brief since 2004, recently scooped the brief to publish The Ramblers' Association title, Walk magazine, and its accompanying website.
River won the account after a four-way pitch that included Future Plus, Seven and the incumbent Think, and will publish the first issue of the magazine in January 2009.