To export products to North America (USA, Canada), products should be certified at the laboratories designated by the US federal government.
Certification can be accomplished at the organizations of SGS, TUV, CSA, UL, Intertek, Nemko-CCL, MET and so on that are belong to *NRTL(National Recognized Testing Laboratory) appointed by *OSHA(Occupational Safety and Health Administration).
* NRTL : these public (or international) organizations are nationally recognized testing laboratories in USA(United States of America)
* OSHA : this governmental organization is institution under the U.S. Department of Labor
The most influential third-party safety certification body in the USA is UL(Underwriters Laboratories). UL mark of USA and CSA mark of Canada accept each other’s certificate.

Like getting a certificate from an institution like UL in the fields of safety and performance test, EMC field test should be certified by FCC(Federal Communication Commission) in USA.
In the compulsory certification system of North America, first method to acquire the FCC certification for transceiver or communication equipment using electromagnetic energy is that it should be tested in the appointed test organizations.
Second method to acquire the FCC certification is the verification of TCB(Telecommunication Certification Body) review.

And although it is not legally required, communication service providers of AT&T, Verizon demand the *CTIA test certification according to the requirement of IEEE Std.
1725(Standard for Rechargeable Batteries for Cellular Telephones), IEEE Std. 1625(Standard for Rechargeable Batteries for Multi-Cell Mobile Computing Devices).
* CTIA : Cellular Telecommunication Industry Association

Use of UL mark