UL divides the wiring used for voice and data systems into "communication wiring and cables"，Abbreviated as CM. This category provides multiple safety levels for specific applications to verify the quality of cable jackets, as follows:

CMP: Fill grade communication cable, which is the highest cable safety level. It has perfect flame retardant ability and emits very low smoke and toxins. According to UL definition, a bundle of CMP cables in Dongguan must self extinguish within 5 meters of the combustion spreading under the condition of forced dense combustion by the fan. CMP cables use Teflo based chemicals to prevent combustion diffusion and minimize the emission of smoke and toxins. Compared to cables with lower UL ratings, this increases the cost significantly. CMP grade cables are used in buildings where cables are laid inside the ventilation and return air ducts. In the event of a fire, the building will not be filled with a large amount of smoke or hazardous toxins emitted by cables. This type of return air mesh is widely used in the United States, but is less commonly used in other parts of the world. CMP grade cables must undergo strict combustion testing: UL910- "Flame Propagation and Smoke Density Test"

CMR: Trunk level communication cable. This is the second ranked cable, which has perfect flame retardant ability, but there is no testing for the emitted smoke and toxins. Except for CMP and cables, CMR cables and all other communication cables use halide based chemicals such as chlorine to prevent combustion diffusion. According to the definition, under the condition of forced combustion of the fan, a bundle of CMR cables must self extinguish within 5 meters of the spread of combustion. The CMR cable jacket is usually made of a certain type of PVC, which emits chlorine gas in the combustion chamber, which exhausts oxygen in the air and extinguishes the flame. CMR grade cables are widely used in trunk applications where ventilation systems are physically separated from wiring systems. This is very common in Asia and Australia. CMR grade cables must undergo intensive flame testing: UL1666- "Flame Propagation Height Test for Cables Installed Vertically Through"

Low Smoke Zero Halogen (LSZH): Another safety level used in the wiring industry is Low Smoke Zero Halogen (LSZH) cables. This security level is defined by ISO/IEC standards and is widely used in Europe. LSZH level, like UL CMP level, tests flame retardancy and emitted gases. As the name suggests, the burning LSZH does not emit halide gases and emits very low levels of smoke. LSZH grade cables can be used for copper cables and fiber optic communication cables, and their structure is similar to UL grade cables

CM/CMG: General Communication Cabling. This is common in the horizontal routing of buildings, where they are typically divided into smaller bundles compared to CMR grade cables. When using halide based chemicals for CM/CMG grade cables, the wire assembly may be affected. According to the definition, in a small bundle of cables, CM/CMG cables must self extinguish within 5 meters of the spread of combustion. The flame was not forced to burn by a fan. CM/CMG grade cable jackets are usually made of a certain type of PVC, which emits chlorine in the combustion chamber. CM/CMG grade cables are commonly used in horizontal routing in the UK, Asia, and Australia. CM/CMG grade cables must undergo CSA FT-4 "Vertical Burning Test"

CMX: Residential communication cabling. This type of cable is limited to residential or other small applications where the number of communication cables used is very small, and these applications generally only lay one cable. CMX grade tools cannot be used for bundled cable applications. CMX grade cables must undergo UL VW1 combustion testing