Depending on the type of equipment that the manufacturers have, FCC certification might be required. The two most common FCC Certifications requirements are FCC Part 15 and FCC Part 68.
Telecommunications equipment has to be tested and be in compliances with FCC Part 68. FCC Part 68 is the FCC Certification for connection to the telephone network. FCC has privatized some of the FCC Part 68 requirements. More information on regulatory compliance can be found at FCC Part 68
The other most common FCC Certification for most electronic equipment is FCC Part 15. FCC Part 15 covers unintentional testing and evaluation as well as low power un-licensed transmitters. More information on this can be found at FCC Part 15
Safety testing and certification is not a FCC Certification requirement. Local states, cities, counties, and municipalities regulate the requirement for safety certification. The Nationally Recognized Testing Laboratory (NRTL) program is set up to cover safety certification. More information on this can be found at Nationally Recognized Testing Laboratory
It is important that manufactures cover the FCC Certification for equipment before the equipment is offered for sale in the United States.