Reuters is reporting Microsoft is to buy privately held Tellme Networks Inc., a speech technology company, to bolster its communications push and enhance searches over mobile phones.

Terms were not disclosed but undisclosed sources valued the Tellme at over $800m

“Mobile search is going to be a huge market,” said Morningstar analyst Toan Tran. “Search on mobile phones is still up for grabs and Microsoft is a big believer in voice being an interface for mobile phones.”