By Joia Shillingford
BBC News business reporter, Cannes
Sony Ericsson has announced it will sell music-playing mobiles under its Walkman brand and will work closely with Sony Connect and Sony BMG, its music division, on content.
Sony Ericsson wants its new mobiles to be as much about music as chat
The company will unveil further details of its Walkman mobile in March.
It made the announcement at the 3GSM World Congress mobile phone trade fair held in the French town of Cannes.
Music by Sony BMG artist Natasha Bedingfield was played over a phone connected to loudspeakers at the event.
Sony Ericsson also launched three third-generation (3G) mobile phones in Cannes, including the Z800, a multimedia phone with a 1.3 megapixel camera, and the K600, a successor to the non-3G T610.
The K600 is aimed at the business market and can use the same mobile accessories as the T610, Chief Executive Miles Flint said.
Sony Ericsson has brought out a card that slots into a PC that can operate on Edge, a high-speed data technology, used on some of today's GSM networks and on four GSM frequencies.
"We will be adding Blackberry mobile e-mail software shortly... starting with the P9110 handset," Mr Flint added.
However, unlike Motorola, the US handset maker, Sony Ericsson does not plan to add voice-over-the-internet features to its mobiles.
Mr Flint said: "We're not adding Skype at this point, but we are watching this whole area carefully."
Motorola is adding Skype to several phones, it said at a press conference in Cannes.
Ron Garriques, president of Motorola's cellphone division, said Motorola would be adding 16 3G handsets this year, compared with six last year, and saw the move from 2.5G to 3G as an opportunity to gain market share.
Separately, the company said it had won 24 contracts in 28 countries for Push to Talk, a walkie talkie-like service, to which it had added instant messaging more familiar to people who like to use text to "chat" on their PCs.
Mr Garriques said he had never been more confident about the company's product portfolio and that its new low-cost phones venture could be profitable.
"Margins do not need to suffer; we are confident we can make a profit with this design," said Mr Garriques, speaking about the company's planned sub-$40 mobile.
Other new four-letter handsets from Motorola include a black version of its very slim clamshell phone, RAZR, a phone called the PEBL (for pebble), which is very rounded and designed to appeal to women, and the SLVR, which it says will be the thinnest candybar-shaped phone.
It said it will launch a major music mobile in Miami in March and the Black RAZR phone will be introduced in time for the Oscars.
Mr Garriques joked that there were other four-letter words he would like to share with the audience and was deliberately dressed down in an anorak.
At one point this was teamed with the company's Oakley sunglasses with built-in Bluetooth which can keep the sun out of one's eyes and answer calls - probably more Los Angeles than Cannes.