The Threat Poses by VoIP Spam

People no longer have absolute trust in using email because of fear of infiltration by spammers who are always ready to use any means to obtain sensitive information in order to swindle the innocent users. Their activity is now spreading to other means of internet communication and the VoIP is not an exemption.
Soon the trust people have in using VoIP will be compromised if urgent attention is not given to combating the alarming rate of VoIP spam. Imagine if 90% of all calls or voice-related messages were, well, spam. Would we even bother to pick up our ringing phones anymore? Just as Caller ID spoofing has become commonplace, it's difficult to identify the validity of callers.
It's important to realize that VoIP spam is easily possible with today's technology already in place. Regular "trunk spam" can be generated using falsified Caller ID (as described above) over the PSTN, just as you or I could place prank calls with advertising for discounted medications, etc. You obviously could be running a 20-year-old key system and still be subject to PSTN spam.
Another vital factor is the type of spam that's aimed at VoIP PBXes, gateways, and servers. Especially with the slow standardization of SIP as an IP-based signaling protocol, many organizations allow "direct" SIP URIs to be used from external sources, trusted or un-trusted. Although, this method of spamming is still rare, it's only a matter of time before the malicious begin to utilize new vectors for propagation.
With the unquestionable focus towards unified messaging, converged infrastructures, and IP-based integration, we'll undoubtedly be fighting new methods of security issues and, the earlier the VoIP service providers realize the urgency in combating this issue, the better.