User guide

August 2001 19
Defining Digit Types
Defining MF Signals
MF digits use combinations of 6 frequencies to make a total of
15 dual-frequency tones, as Table 5 shows. MF signals are also
called R1-MF.
Table 5. MF Tones
COs in the United States, Canada, and Japan generally use MF
digits to establish calls. Telephony systems that use T1 lines
also use MF digits to communicate with the CO. Once the call is
established, callers use DTMF digits to navigate telephony
applications.
MF signaling uses five signals in addition to digits 0 through 9.
The key pulse (KP) signal comes at the beginning of any digit
string and prepares the receiving end to accept the digits. The
start signal (ST) signal comes at the end of any digit string. The
remaining three signals (spare) are reserved for the national
identity of the receiving end.
Digits Frequencies
700 900 1100 1300 1500 1700
1xx
2x x
3xx
4x x
5xx
6xx
7x x
8x x
9xx
0xx
spare x x
spare x x
KP x x
spare x x
ST x x