From the IRS:
You may be one of the nearly 160 million phone customers who can request a refund of the 3% federal excise tax paid on long-distance and bundled phone service billed after Feb. 28, 2003 and before Aug. 1, 2006. Federal long-distance excise taxes paid on cell phone, land line, fax, Internet phone service and bundled service all qualify for the refund. Phone plans that provide both local and long-distance service for either a flat monthly fee (the charge for local service is not separately stated) or a charge that varies with the time for which the service is used are considered bundled services.
You can request the refund in one of two ways: Calculate the actual amount of tax you paid, as shown on your phone bills and other records, or request a standard amount, ranging from $30 to $60, based on the number of personal exemptions you claim.