R2 Signaling Tones and Pulse Code Modulation Line Signaling

This chapter describes the R2 signaling tones generated and detected by the MFCR2 transceiver cards, and the R2 pulse code modulation (PCM) 2-bit line signaling transmitted and received by E1 spans.

Forward and Backward Signaling Tones

Table 2-1 through Table 2-4 provide R2 signaling information based on ITU Q.441 as it applies specifically to the Guangdong telephone network.

Note All R2 tones are -8.86 dBm per component.

Table 2-1: R2 Signaling Group I Forward Signals

Token Data Field	Designation	Frequencies	Digit Meaning	KA^¹	KC^²	KE^³
1	G-I-1	1380 + 1500 Hz	Digit 1	Regular	Not applicable
2	G-I-2	1380 + 1620 Hz	Digit 2	Immediate Meter
3	G-I-3	1500 + 1620 Hz	Digit 3	Immediate Printer
4	G-I-4	1380 + 1740 Hz	Digit 4	Spare
5	G-I-5	1500 + 1740 Hz	Digit 5	Free
6	G-I-6	1620 + 1740 Hz	Digit 6	Spare
7	G-I-7	1380 + 1860 Hz	Digit 7	Spare
8	G-I-8	1500 + 1860 Hz	Digit 8	Priority Regular
9	G-I-9	1620 + 1860 Hz	Digit 9	Spare
10	G-I-10	1740 + 1860 Hz	Digit 0	Priority Free
11	G-I-11	1380 + 1980 Hz	Not applicable	Spare	Spare	H
12	G-I-12	1500 + 1980 Hz	Not applicable	Spare	ATME	Spare
13	G-I-13	1620 + 1980 Hz	Not applicable	Test	T	T
14	G-I-14	1749 + 1980 Hz	Not applicable	Spare	Priority	Spare
15	G-I-15	1860 + 1980 Hz	End of Number	Spare	Satellite	Not applicable

¹Calling party category.
²Call category used between toll exchanges; used to indicate a priority call or a test call.
³Call category from toll to local, or from local to local; used to indicate a test call.

Table 2-2: R2 Signaling Group II (KD) Forward Signals

Token Data Field	Designation	Frequencies	Meaning
1	G-II-1	1380 + 1500 Hz	Semiautomatic toll operators call
2	G-II-2	1380 + 1620 Hz	Toll automatic call
3	G-II-3	1500 + 1620 Hz	Local call
4	G-II-4	1380 + 1740 Hz	Local priority call
5	G-II-5	1500 + 1740 Hz	Operators check the calling party's number in SA call
6	G-II-6	1620 + 1740 Hz	Test call
7	G-II-7	1380 + 1860 Hz	Not applicable
8	G-II-8	1500 + 1860 Hz
9	G-II-9	1620 + 1860 Hz
10	G-II-10	1740 + 1860 Hz
11	G-II-11	1380 + 1980 Hz
12	G-II-12	1500 + 1980 Hz
13	G-II-13	1620 + 1980 Hz
14	G-II-14	1740 + 1980 Hz	Not applicable
15	G-II-15	1860 + 1980 Hz	Not applicable

Table 2-3: R2 Signaling Group A Backward Signals

Token Data Field	Designation	Frequencies	Meaning
1	A-1	1140 + 1020 Hz	Send next digit (n+1)
2	A-2	1140 + 900 Hz	Start from first digit
3	A-3	1020 + 900 Hz	Number complete, change over to reception of Group-B signals
4	A-4	1140 + 780 Hz	Network congestion
5	A-5	1020 + 780 Hz	Vacant number
6	A-6	900 + 780 Hz	Send KA and calling party's number¹
7	A-7	1140 + 660 Hz	Not applicable
8	A-8	1020 + 660 Hz
9	A-9	900 + 660 Hz
10	A-10	780 + 660 Hz
11	A-11	1140 + 540 Hz
12	A-12	1020 + 540 Hz
13	A-13	900 + 540 Hz
14	A-14	780 + 540 Hz
15	A-15	660 + 540 Hz

¹First A-6 is an instruction to send KA signal. Successive A-1s are to send the calling party identity as G-I signals.

Table 2-4: R2 Signaling Group B (KB) Backward Signals

Token Data Field	Designation	Frequencies	When KD=1, 2, or 6	When KD = 3 or 4
1	B-1	1140 + 1020 Hz	Idle	Idle
2	B-2	1140 + 900 Hz	Busy, local duty	Spare, using called party control or first party control
3	B-3	1020 + 900 Hz	Busy, toll duty	Spare
4	B-4	1140 + 780 Hz	Congestion	Called subscriber busy or equipment congestion
5	B-5	1020 + 780 Hz	Vacant number	Vacant number
6	B-6	900 + 780 Hz	Spare	Called subscriber idle using calling party control
7	B-7	1140 + 660 Hz	Not applicable	Not applicable
8	B-8	1020 + 660 Hz
9	B-9	900 + 660 Hz
10	B-10	780 + 660 Hz
11	B-11	1140 + 540 Hz
12	B-12	1020 + 540 Hz
13	B-13	900 + 540 Hz
14	B-14	780 + 540 Hz
15	B-15	660 + 540 Hz

Pulse Code Modulation Line Signaling

Table 2-5 describes the 2-bit, channel-associated pulse code modulation (PCM) line signaling used by VCO/4K systems equipped with E1 interface cards. This digital R2 signaling complies with Shenzhen Specification NTP-8445, May 1990, Appendix D. Forward signals are used by originating or outgoing ports, while backward signals are generated by incoming ports. For more information on E1 cards, refer to the Cisco VCO/4K Card Technical Descriptions manual.

Table 2-5: R2 Pulse Code Modulation Line Signaling

Signal	Exchange Signaling Forward Backward
	Af Bf	Ab Bb
Idle	1 0	1 0
Seize	0 0	1 0
Seize Acknowledge	0 0	1 1
Answer	0 0	0 1
Flash (for 600 ms)	1 0	0 1
Called Party Clear	0 0	1 1
Called Party Re-answer (before time-out)	0 0	0 1
Calling Party Clear (before called party)	1 0	0 1
Calling Party Clear (after called party)	1 0	1 1
Release Guard	1 0	1 0
Blocking	1 0	1 1

Table of Contents

R2 Signaling Tones and Pulse Code Modulation Line Signaling

Forward and Backward Signaling Tones

Pulse Code Modulation Line Signaling