Hi Aadhil,
Change Management - Usually includes any changes made to the existing infrstraucture. In IPT, for example the cucm cluster is installed and when you want to provision phones and voice mail for new users , that comes under change management
Incident Management - Any issues in the existing voice infra comes under this. For example, PRI goes down in any of the voice gateways is an incident
Service Management includes designing, delivering and managing infrastructure as a whole.
HTH
Rajan
Pls rate all useful posts
