The Law Offices of Thomas Crowe has a simple explanation about form 499a (USF payments) here.
Virtually all telecommunications providers, including long distance resellers, prepaid card providers, wireless providers, Mobile Virtual Network Operators (MVNOs), and now interconnected VoIP providers, seeking to provide service in the U.S. must first register to do so with the FCC. Registration is accomplished by filing with the Universal Service Administrative Company (USAC) a signed copy of selected portions of the FCC Form 499-A.
The form 499 is due quarterly. (see schedule here).
Form 477 is in flux right now as the FCC is taking comments on how to improve data collection after the court, Congress and the GAO gave Martin a beating about his lousy data. Anyway.... the form 477 has to be March 1 and Sept. 1. (I have written about this before).
There are also new privacy rules for carriers called CPNI (Customer Proprietary Network Information). "This filing must be made annually with the Enforcement Bureau on or before March 1 in EB Docket No. 06-36, for data pertaining to the previous calendar year." The fines for not filing these forms are high. It is easier and cheaper to have your attorney file for you. I would suggest Kris Twomey or Jonathan Marashlian at The CommLaw Group.