Networking vendor NEC has warned businesses that telephony spam levels are about to soar.
Telephony spam could soon comprise more than half of all phone calls, the company said, potentially causing worker productivity to plummet.
While junk messages are already prevalent in the data world, they have largely failed to affect telephony because it would be too costly, as senders would have to pay for each call. But as more telephony is delivered over IP networks, the volumes of spam aimed at telephony users is likely to explode, according to NEC.
Juergen Quittek, senior manager at NEC Network Labs, said: "Now the telephony world is migrating to internet telephony, botnet platforms can be used to create spam phone calls as well as emails." Quittek cited statistics saying the percentage of phone calls that are spam will soon rise to between 40 and 70 per cent.
NEC has developed a software add-on to its PBXs, which it said will stop up to 99 per cent of spam phone calls. The software uses a variety of techniques to detect spam calls. For example, if too many calls originate from one IP address, those calls can be sent to voicemail or rejected. The software also includes a policy tool to whitelist or blacklist callers by caller ID or IP address.
Another approach "answers" incoming calls with a fake ringing tone. This will trigger a spam message to start playing, while a human caller won't detect any change and will remain silent. Spam calls will then be rejected by the PBX without the recipient's phone ringing.
Several other companies are also developing techniques for blocking telephony spam, including security products vendor Checkpoint, and Eyeball Networks, a Canadian company which has developed a server specifically designed to stop Spit (spam over internet telephony).
But Cisco Systems, the vendor which has sold the most IP telephony systems, is less convinced about the threat. Mick Stevens, UK security market manager at Cisco, said: "We have not seen activity [of this nature] that has put people on the back foot. We have nothing along the lines of what NEC has developed."