GO to Cisco Unified Serviceability, Tools --> Service Activation.
Make sure Cisco Extension Mobility service is enabled. If not enabled, enable it.
2. CREATING THE SERVICE
a. GO to CUCM Administration, Device --> Device Settings --> Phone Services.
b. Add new. Enter the name such as EM or Extension Mobilty
c. Enter the URL: URL: http://<CUCM IP>:8080/emapp/EMAppServlet?device=#DEVICENAME#
d. Choose XML Service and Standard IP Phone Service as the Service Category and Service Type respectively.
e. Click Save.
3. CONFIGURING PHONES
a. Go to Device --> Phone, open the phone where you want to enable the service.
b. Related links on top of the page, select Subscribe/Unsubscribe Services and click GO.
c. Select the service created on CREATING THE SERVICE above.
d. Subscribe and Save.
e. Make sure 'Enable Extension Mobility' is checked on the Phone.
NOW PHONES HAVE SERVICE ENABLED, BUT USERS ARE STILL NOT ENABLED FOR EM. NOW LETS ENABLE USERS
4. CONFIGURING USER DEVICE PROFILE (UDP)
a. GO to Device --> Device Settings --> Device Profile
b. Add New
c. Select Phone type (according to the phone type where the user will log into)
d. Select Device Protocol <-- You will only be presented with the Protocl option if the Phone is question supports both SIP and SCCP.
e. Select a name: such as "User1" and fill in all required fields <-- Most of these options are similar to creating a phone - only difference is there is no MAC Address option here.
f. Related links on top of the page, select Subscribe/Unsubscribe Services and click GO.
g. Select the service created on CREATING THE SERVICE above.
h. Click on 'Line  - Add a new DN' and enter line information (just like you would do on an IP Phone)
i. Click Save.
5. CONFIGURING USERS
a. Go to User Management --> End Users
b. Open an existing user or create a new one.
c. Make sure userid, password, pin, and phone number are configured.
d. Also under 'Extension Mobility' select "User1" (or whichever user was created on CONFIGURING USER DEVICE PROFILE) and move it down to the controlled profiles section.