In a somewhat surprising and aggressive move, Sony Ericsson is set to unveil an unlimited music downloading service for its cell phones this month, the UK’s Financial Times reports, in an attempt to stem its declining market share.

Nokia’s service, due to launch in October in the UK, will let owners of specific handsets download as much music as they want during the first 12 months of use. Sony Ericsson, in the meantime, is in talks with the major labels to come up with a similar arrangement, the report said.

It couldn’t come at a more pressing time for the struggling handset vendor. “Sony Ericsson’s market share is shrinking,” Dan Cryan, an analyst at Screen Digest, said in the report. “If everybody is launching ‘all you can eat’ services, which make handsets more attractive to end users and to operators, they don’t have much choice, especially when so much of their brand value is built around the Walkman.”