Multi-frequency
From Wikipedia, the free encyclopedia
In telephony Multi-Frequency (MF) is an outdated, in-band signaling technique. Numbers were represented in a two-out-of-five code and received by a Multi-Frequency Receiver. MF was used for trunk signaling, and is a precursor of modern DTMF "touch" tones now used for subscriber signaling.
MF signaling includes R2 signalling, R1 (in North America), and Signaling System No. 5.
For details on R1, see blue box.
| Telephony signals Dial | Ringing / Ringback | Busy | Congestion / Reorder | Special information | Off-hook | Ring | DTMF | 2600 Hz |
