TELTONE

ELECTRICAL DEVICES FOR USE IN OR WITH TELEPHONE AND SIMILAR COMMUNICATIONS SYSTEMS-NAMELY, MULTI-FREQUENCY TONE ADAPTION AND CONVERSION APPARATUS FOR ADDING MULTI-FREQUENCY TONE CAPABILITY TO ROTARY DIAL TELEPHONE SYSTEMS OR PARTS THEREOF, MULTI-FREQUENCY TONE RECEIVERS, MULTI-FREQUENCY TONE GENERATORS, KEY SYSTEM TONE INTERCOMS, MULTI-FREQUENCY TONE AMPLIFIERS, VOICE OPERATED SWITCHES, AND SERVICE OBSERVING SYSTEM

MULTI-FREQUENCY TONE TEST SETS