Even non-transmitting devices can be "unintentional radiators" as per the FCC. Using pre-licensed components doesn't exempt you from testing and appropriate cer

Even non-transmitting devices can be "unintentional radiators" as per the FCC. Using pre-licensed components doesn't exempt you from testing and appropriate certification -- you're on the hook for the entire product. Furthermore, submodules might only be certified for certain configurations which your device may violate, and thus you would require certification. Basically, there are three kinds of procedures you need to worry about: verification (the least intrusive, requires that the manufacturer do tests but does not require approval); declaration of conformity (requires a certified test lab certify the product); and certification (the "FCC Code" -- requires an application to the FCC or a TCB, including technical specs and official test results). The only way to be sure is to have engineers on staff or on contract with experience in licensing issues. By the way, if you're selling a kit product, you may be exempt from much of the approval process, which may influence your decision.