Open a blank document on your computer in a word processing software program. Press the return button five or six times and enter the current date. Press the return button twice and type the name and mailing address of your telephone service provider in Arial font, size 12.
Press enter twice and type "Dear <Telephone Company Name>:" Press enter twice and type "Re: Account <Your Account Number>." Press enter twice and begin typing the body of your letter.
Type your cancellation request in wording similar to the following: "I would like to have my phone service for phone number ###-###-#### cancelled effective immediately upon your receipt of this letter."
Press enter three times and type "Sincerely," press the enter button twice and type your first and last name. Press return and type your mailing address.
Print off two copies of the letter and save the electronic document to a place where you can easily find it later, if needed. Sign one of the copies, place it in an envelope, address the envelope to the location where the company receives correspondence about customer accounts and take the envelope to your local post office. Request that the letter be sent with a delivery receipt so that you will have proof of delivery and a date when your cancellation letter was received.
Watch your account to see that your service is cancelled on the date that your letter is received or by the next day at the latest. Contact your phone service provider if your service is not cancelled and demand your service be cancelled immediately. Mention your letter and the delivery receipt. Threaten to report the company to the Better Business Bureau and your State Attorney General if your account is not cancelled immediately.