UK outfit Cellcrypt has updated its voice-over-IP (VoIP) call security software for mobile phones to support Windows Mobile hardware for the first time.

Users on that platform are now able to run a special application in advance of making a mobile phone call, and take advantage offend-to-end encryption as long as the person they are calling also has it installed.

Calls are scrambled using RSA 2048 or AES 256-bit encryption, securing them from eavesdroppers to the same security standards were the call being made using a VoIP client on a PC. The communications channel used - GSM, 3G, GPRS or Wi-Fi - is irrelevant to the security or, the company claims, call clarity.

"It is common for organisations and individuals to protect their valuable computer data using encryption technologies; but by and large sensitive voice conversations are only lightly protected and vulnerable to eavesdropping," said Cellcrypt's Lauri Monroy.

"Use of Cellcrypt Mobile provides the confidence that phone calls, whether in the mobile or office environment, at home or overseas, within or between departments and with partners, suppliers and friends, are all protected end-to-end," he said.

The company's Cellcrypt Mobile 3.2 has supported Nokia/Symbian 9.1 handsets since its quiet launch earlier this year, now widened beyond that base in version 4.0. Future versions are promised to support the BlackBerry.

With the core market of government in mind, the company is also submitting the software for NIST FIPS 140-2 certification, necessary to win contracts in that sector, especially in the standard's home territory, the US.

Pricing starts at £695 for a single-user license (two are required for each call), coming down for larger volumes of users.