Complete the following steps.
Go to My Account, enter your User ID and Password, and then click Sign In.
Note: If you do not remember your User ID or Password, or experience an issue signing in, see Recover Your Cox User ID or Reset Your Cox Password.
Scroll down to the Manage your services & equipment section and click the Mobile icon.
Result: The Mobile Account page displays.On the Mobile Account page, under the Lines section, look for the mobile phone number you would like to update and click the Manage line link.