 |
 |
|
 |
|
|
|
|
|
The telephone set has oscillators for a high-frequency group (high group frequencies) and those for a low-frequency group (low group frequencies). Pressing a push-button key operates a pair of high-group and low-group oscillators corresponding to the number, generating the mixed signal to the exchange.
For example, the signal for number "0" is the combination of two frequencies shown above.
