Establishments primarily engaged in manufacturing wire telephone and telegraph equipment. Included are establishments manufacturing modems and other telephone and telegraph communications interface equipment. Establishments primarily engaged in manufacturing cellular radio telephones are classified in Industry 3663.

• Auto-transformers for telephone switchboards
• Carrier equipment, telephone and telegraph
• Communications headgear, telephone
• Data sets, telephone and telegraph
• Facsimile equipment
• Headsets, telephone
• Message concentrators
• Modems
• Multiplex equipment, telephone and telegraph
• Switchboards, telephone and telegraph
• Switching equipment, telephone
• Telegraph office switching equipment
• Telephone answering machines
• Telephone central office equipment, dial and manual
• Telephone dialing devices, automatic
• Telephone sets, except cellular radio telephone
• Telephone station equipment and parts, wire
• Telephones, sound powered (no battery)
• Telephones underwater
• Toll switching equipment, telephone