The transmitter frequency range is 200 Hz to 3904 Hz with a resolution of 1 Hz.
The receiver frequency range is 200 Hz to 4100 Hz with a resolution of 1 Hz.
The transmitter and receiver level ranges are +10 dBm to 40 dBm with a resolution of 0.1 dBm

The 4940A Transmission Impairment Measuring Set (TIMS) tests the capability of a telephone circuit to handle data. It measures loss, dropouts, gain hits, phase hits, phase jitter, noise-with-tone, noise-to-ground, frequency shift, message circuit noise, 3-level impulse noise, attenuation distortion, envelope delay distortion, and single frequency interference.

The 4940A is also capable of running a comprehensive self-check. The 4940A does complete analog testing of voice and data channels. It is also compatible with North American Standard. .