5.18.1.3. The Meaning of the MFC-R2 Signals According to UIT Q.441 
The following table lists the meanings of the forward (Groups I and
II) signals and the backward (Groups A and B) signals. This table is
a compilation of the CCITT tables 6 to 9/Q.441.
|
Signal
|
Group I
|
Group II
|
Group A
|
Group B
|
|
1
|
Digit 1
|
STN without priority
|
Send next digit (n+1)
|
Spare for national use
|
|
2
|
Digit 2
|
Subscriber with priority
|
Send last but one digit (n-1)
|
Station number modified
|
|
3
|
Digit 3
|
Maintenance equipment
|
End-of-dial
Reception of B signal
|
Station busy
|
|
4
|
Digit 4
|
Spare
|
Congestion
|
Congestion
|
|
5
|
Digit 5
|
Operator
|
Send calling party's category
|
Port not configured
|
|
6
|
Digit 6
|
Data transmission (national)
|
End-of-dial, set-up speech condition (with call
charges)
|
Station free with call charges
|
|
7
|
Digit 7
|
STN or AC without forward transfer capability
|
Send last but two digit (n-2)
|
Station free without call charges
|
|
8
|
Digit 8
|
Data transmission (international)
|
Send last but three digit (n-3)
|
Station faulty
|
|
9
|
Digit 9
|
Priority STN (international)
|
Spare for national use
|
Spare for national use
|
|
10
|
Digit 10
|
Operator with forward transfer capability
|
Spare for national use
|
Spare for national use
|
|
11
|
Access to incoming operator (Code 11)
|
Spare for national use
|
Send country code
|
Spare for national use
|
|
12
|
a) Access to delay operator (Code 12)
b)
Request not accepted
|
Spare for national use
|
Send language or discriminating digit
|
Spare for national use
|
|
13
|
a) Access to test equipment
b) Satellite
link not included
|
Spare for national use
|
Send type of international R2 register
|
Spare for national use
|
|
14
|
a) Incoming half-echo suppressor required
b)
Satellite link included
|
Spare for national use
|
Is an incoming half-echo suppressor necessary?
|
Spare for national use
|
|
15
|
a) End of pulsing
b) End of identification
|
Spare for national use
|
Internationally congested
|
Spare for national use
|