From the FCC website:
FCC Form 499-A Telecommunications Reporting Worksheet
Need to file if:
You must file if you are defined as a telecommunications carrier under section 3(44) of the Telecommunications Act or if you offer any interstate or international telecommunications services or interconnected Voice over Internet Protocol (VoIP). The definition is very broad and covers many firms that have no other contact with the FCC. Wireline, wireless, wholesale only, resale, interstate, and international carriers (including ILECs, CLECs, prepaid card, prepaid wireless phone and pay telephone providers) as well as some other telecommunications providers must file.
1) If it were my business, I would file.
2) Things are getting tougher all the time, as the authorities are increasingly concerned about spoofing, swatting, general fraud, and homeland security issues.
3) At a minimum, discuss with an attorney familiar with telecom issues.
4) I would not rely on the presence or absence of a 499 from any particular provider here.