The Business Phones 24E and 50E allowed the same system to accommodate an arbitrary combination of tone-dialing and pulse-dialing lines. Each of these models incorporated a microprocessor, providing a variety of service features. The Business Phone 24E allowed up to eight central office lines and up to 24 units to be connected. The Business Phone 50E allowed up to 16 central office lines and up to 50 units to be connected. For each model, color panels were available in five colors, allowing each unit to be distinguished by color for its application.

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