No more SPIT!

This article is not a roaring plea from baseball fans. No, this article is about SPam over Internet Telephony or as it is often shortened—SPIT. Those annoying, unsolicited messages that clutter your email inbox have an ugly cousin that seeks to bombard your digital phone messaging system with pre-recorded messages and cause much more damage. The problem with SPIT is that if it isn’t controlled it can quickly eat up your valuable bandwidth and clog up your system, which can prevent legitimate callers from reaching you. There are software programs on the market to tackle SPIT. Many of these function similar to the tools used to control and prevent email spam.

Action VoIP Providers Can Take

As a subscriber of a hosted PBX service, your VoIP service provider should offer you the best defense against SPIT. Any VoIP service provider with sophisticated networking has the power to identify a significant amount of SPIT. A network firewall and intrusion detection system could monitor your inbound call traffic patterns and issues warnings to keep the system free of SPIT. Setting up a network firewall rule to block the source of offending traffic will provide some deterrent from the spammer.The problem with this approach is that identification and blocking can not be performed automatically, making it labor intensive especially in larger hosted VoIP service provider environment because most pattern matching algorithms return false positives.

A less popular form of defense against SPIT that VoIP service providers offer is a form of authentication used to detect machine-based calls. This feature is used in conjunction with a whitelist (list of authorized callers). When you receive a call from an unauthorized caller, an automated system requires the caller to answer a question before the caller is connected to you. This type of system is popular with customer service centers. You have undoubtedly had to provide some identifying information about yourself (phone number, name, etc…) before being connected to a customer service representative.

Action You Can Take

It is very common for email providers to filter suspect email to a spam folder. A comparable action that VoIP providers can take is to provide a blocking feature. When you receive a call and determine it to be SPIT, you can specify that the phone service block incoming calls that match that number. If you receive calls from a particular area code, you can block calls from the entire area code. Note that you won’t receive any calls from the blocked area code. Blocking works, but expert spammers are often relentless and will often use other techniques to reach you.

Whitelisting is another form of call blocking. Instead of creating a list of “bad” numbers, you create a list of authorized callers. When this feature is enabled, you will only receive calls from your authorized list. This feature is very restrictive and may not offer businesses the best strategy against SPIT.

The difficulty in tracking the origination of a caller using VoIP is one of the major headaches of preventing SPIT. Less tech savvy perpetrators of may conceal their identity by simply blocking their caller ID. Once enabled, the anonymous call blocking feature stops these calls before they reach your phone. This feature is a common offering with VoIP service providers.

In the Future

There are other promising technologies on the horizon that may offer a better defense against SPIT in the future. Until those services are available, the best strategy for dealing with SPIT is to use a mixture of the tools that are currently available.