However, as MNOs start to enter the third phase of the sigmoid or S-curve growth model as service providers, SMS in many markets is starting to enter the detrimental "substitution" stage of decline where users are finding new, better and cheaper alternatives to SMS, namely Over The Top (OTT) messaging providers such as Whatsapp, Kik, Snapchat and even Facebook Messenger along with a seemingly endless array of other OTT apps. According to McKinsey, users in South Korea and The Netherlands have already tipped away from SMS where the move to OTT messaging apps is having a material impact on the MNOs SMS volumes and revenues. Essentially, people are texting so much less that it is impacting the MNOs' business.