Contact your mobile service provider, verify your identity and current number, and request to change your phone number. Mobile companies often charge a fee of $15 to $20 to perform this service, as of 2016. Some companies also let you log in to your account online and change your number through the website, which sometimes negates the fee. It often takes three to four hours for the new number to take effect.
Changing your phone number through the online system does not allow you to choose your new number. Call the customer service department of your mobile provider if you want to choose a new number, and see if the representatives there can help you.
Once a new number is assigned, it can still take an additional three days for that number to appear on caller ID when you call someone. Mobile carriers often put restrictions on how often you can change your phone number. For example, Sprint does not let you change your number more than three times in 30 days.
If you need to change the phone number for a contact in your phone, go to your Contacts menu, and select the contact whose number you want to change. Select Edit Contact, and enter in the new number you want to use for that person. Delete the old number if the person does not use it anymore.