It isn’t just the rock bottom price that attracts business users to VoIP according to IP Centrex Vendor 8el. That doesn’t mean businesses are not attracted by the low prices of VoIP. It means that VoIP is maturing as a business and users are looking for more features from it. In the near future, what will differentiate VoIP from other similar offerings or VoIP from VoIP is what features the service offers.
Differentiable VoIP features include a temporary voice mail greeting with a configurable number and also enhanced centralized unified messaging. The king of features remains the quality of voice transmission though. This is what business users want the most of. That there is great room for improvement in international calls and business conferences is a common opinion. High definition audio quality could be the next big “feature” of VoIP.
This interesting analysis features in fiercevoip.com.

True, Voip is one the major market for Telecom services.
Telecommunication Services