O2 has launched Fixed Number Anywhere, which forwards calls from a landline immediately and cost free to a mobile phone.
The idea is for business people that want to seem local and professional, but are constantly on the move, can now keep track of their calls.
O2 estimates 70 per cent of businesses have a fixed landline, although many are spending increased amounts of time away from the desk, with costly call forwarding in place.
However, those calling the landline won't be charged at mobile rates, which many people still see as prohibitively high.
Businesses can link up to five landline numbers to a mobile phone, and up to ten mobiles can be synchronised to the fixed line to ring simultaneously or in priority order.
Customers bringing an existing 01 or 02 BT line, as well as taking out a new mobile contract, will get the service for free.
Simon Devonshire, Head of SME Marketing for O2, said: "Desk phones were great when business was done from a desk but for the vast majority of small businesses the fixed nature of a landline is at odds with how they operate day to day.
"By converging a fixed landline number with a mobile service, small businesses can continue to maintain an image of being a local business, which is valued by customers, whilst maintaining the flexibility and mobility that has enabled them to adapt to and thrive in the current climate."