British femtocell company Ubiquisys rolled out a new smartphone accessory – the attocell, a personal cell phone signal that allows international travellers to make and receive calls without paying roaming charges.

The Google-backed start up company, which develops 3G and LTE intelligent cells, says in its blog that the world’s first attocell doesn’t incur roaming charges because the phone is not roaming, and does not connect to the visiting country’s networks. Instead it travels over the internet to the home country. In most cases where the attocell would be used, like in a hotel room, people are already using a Skype- type or similar service rather than roaming.

Although developed specifically for the iPhone, the company says attocell works with any 3G phone, and has also been tested with Blackberry, Nokia and Android smartphones.

Formed in 2004, the company announced the first residential femtocell for less than $100 in December 2009. Ubiquisys other investors include tier 1 VCs and T-Mobile. The company counts Nokia Siemens Networks, NEC and Ericsson among its engagement partners.

Ubiquisys says the device with a range so tiny it can be used anywhere that your laptop has an internet connection. The attocell connects to a user’s laptop via USB that provides power and an internet connection.

A hotel room or an office would be good places to use an attocell. This is also where mobile reception tends to be least effective. The attocell is not really designed for use on the move, says the company.

The device analyses the IP address and radio environment to determine which country it is in, and sets its 3G radio power accordingly to below the licenced level. In some countries its range will be just 5 millimeters, in other countries, it could cover a whole room.

In 5mm mode, the traveller simply lays the iPhone on top of the device and the phone connects automatically, just like a regular femtocell. Calls can be made using a Bluetooth or wired headset , or by using the iPhone’s speaker.

Like Ubiquisys femtocells, the attocell continuously monitors its radio environment to ensure that there is zero impact on existing mobile networks, says Ubiquisys. This intelligence, combined with its tiny power output, is likely to make the attocell exempt from regulatory controls and the requirement for type approval.

The attocell innovation is a direct response to meet a specific requirement from mobile operators, says chief executive Chris Gilbert.

The company says it will showcase the attocell to customers in Barcelona, at February’s Mobile World Congress.