208 million IMS-based subscriber lines deployed in carrier networks worldwide

The report says that an estimated 25 percent of the total subscriber capacity in wireline networks has migrated to VoIP. Of the 25 percent, around 14 percent is comprised of softswitch based subscriber lines and remaining 11 percent is comprised of IMS based subscriber lines.

Obviously most of the IMS action surrounds the wireline market where the packetization has been pushed to the edge through broadband deployment. For convergent operators, IMS solves time to market issue. For mobile operators, the short term driver is to launch the enhanced communications services like RCS. But that is a major market driver. It is not a sufficiently large enough motivation to go for IMS deployment. But since the industry chose IMS to carry VoIP within mobile networks the mid term driver for IMS is VoLTE.