R2 Signalling 6p4u2r

R2 Signalling

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E1 - Frame Structure 1 Multiframe, 4096 Bits 2 msec 16 Frames 1

8

16

1 Frame, 256 Bits—125us, 32 Time Slots 0

31

1 Channel Time Slot Bit Rate = 2.048 Mbps

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E1 - Frame Structure Time Slot 0 Synchronization 0011011 Bits 2 to 8

16th Time Slot Contains Multi-Frame Alignment Signal

ABCD signalling Bits for Time Slots 1 and 17

16 Frames per Multiframe

ABCD signalling Bits for Time Slots 15 and 31 32 Time Slots—125usec

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E1 - Frame Structure Signalling

8 bits TS0

TS1

Framing, Synch & Alarms

TS2

•••

TS16

•••

TS30 TS31

256 bits = 32 Time Slots = 125 µsec

• Time Slot 0 Frame Synch CRC4 Alarms National Specific Stuff

• Time Slot 16 - Signalling Presentation_ID

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Time Slot 0 – Framing Bit number 1

2

3

4

5

6

7

8

Si

0

0

1

1

0

1

1

Sa6

Sa7

Sa8

Alternate frames

Frame containing the frame alignment signal

Frame not containing the frame alignment signal

(Note 1)

Frame alignment signal

Si

1

A

(Note 1)

(Note 2)

(Note 3)

Sa4

Sa5

(Note 4)

Note 1 – Si = bits reserved for international use Note 3 – A = Remote alarm indication. In alarm condition, set to 1 Note 4 – Sa4 to Sa8 = Additional spare bits Presentation_ID

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5

Channel Associated Signalling E-1

16th Time Slot

Supervisory/State Line Signalling Address Signalling Signalling (DTMF, R2/MF) and Audio Presentation_ID

Supervision On/Off Hook

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A, B, C and D bits

6

Time Slot 16 -- Channel Associated Signalling (CAS) Time slot 16 of frame 0 0000xyxx

Time slot 16 of frame 1 abcd channel 1

abcd channel 16

Time slot 16 of frame 2 abcd channel 2

abcd channel 17

–––

–––

Time slot 16 of frame 15 abcd channel 15

abcd channel 30

• x = Spare bit, to be set to 1 if not used y = Alarm indication; in an alarm condition, set to 1 • CAS Multiframe consists of 16 frames independent of the CRC-4 Multiframe delineated in TS0 • When bits b, c or d are not used they should have the values: b = 1, c = 0, d = 1

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ITU-T Recommendations 1.

Q.400: Definitions

2.

Q.411: Analog line signalling - (Continuous)

3.

Q.421: Digital line signalling

4.

Q.440: signalling

5.

Q.450: Multi-Frequency Signalling Equipment

6.

Q.460: Signalling Procedures

7.

Q.490: Testing and Maintenance

8.

Supplement 5: Analog line signalling with Metering

9.

Supplement 6: Digital line signalling with Metering

10. Supplement 7: Semi-Compelled / Non-Compelled signalling and Pulsed Analog line signalling

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Two parts of R2 signalling

• Line Signalling (Supervisory Signals) • Inter Signalling (Call Setup Control Signals)

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Line Signalling yoghourt(config-controller)#cas-group 0 timeslots 1-31 type ? e&m-fgb E & M Type II FGB e&m-fgd E & M Type II FGD e&m-immediate-start E & M Immediate Start fxs-ground-start FXS Ground Start fxs-loop-start FXS Loop Start p7 P7 Switch r1-modified R1 Modified r2-analog R2 ITU Q411 r2-digital R2 ITU Q421 r2-pulse R2 ITU Supplement 7 sas-ground-start SAS Ground Start sas-loop-start SAS Loop Start

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Line Signalling • Line Signalling (Supervisory Signals) The handshaking between two offices for call setup and termination Signals are “On-Hook”, “Off-Hook”, LineSeizure”, “Answered”, ... In timeslot 16 of the multiframe (A, B, C and D bits)

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Line Signalling • Digital: where A & B bits are used (ITU-T Q.421) • Analog: (Continuous): where a Tone or A-bit is used (ITU-T Q.411) Analog is not really analog, but it is called so because it reflects the on/off switching of a tone (tone-on-idle) in FDM (Frequency Division Multiplexing) circuits that were common before TDM circuits. For a given channel, the tone-on or off is mapped to A bit for the respective direction Presentation_ID

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Line Signalling

• Pulsed: where a Tone or A-bit is pulsed (ITU-T Supplement 7) Pulsed is reflecting the same states as the analog signalling, however, Analog is steady state, and Pulsed is not, it just sends a single pulse to reflect a state change

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Backward And Forward • Forward: towards the called party • Backward: towards the calling party Forward

Backward

calling

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called Cisco Systems Confidential

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R2 Digital Signalling code State of the circuit

Forward

Backward

af

bf

ab

bb

Idle/R eleased

1

0

1

0

Seized

0

0

1

0

Seizure acknowledged

0

0

1

1

Answered

0

0

0

1

C lear-back

0

0

1

1

C lear-forward

1

0

0

1 or

B locked

Presentation_ID

1

0

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1

1

1

1

15

Example Digital Signalling

May 19 10:44:50.831: neat msg at slot 0: (3/8): Rx SEIZURE May 19 10:44:50.975: neat msg at slot 0: (3/8): Tx SEIZURE_ACK May 19 10:44:56.327: neat msg at slot 0: (3/8): Tx ANSWERED ... May 19 10:46:19.503: neat msg at slot 0: (3/8): Tx BWD_CLEAR May 19 10:46:21.399: neat msg at slot 0: (3/8): Rx IDLE May 19 10:46:23.423: neat msg at slot 0: (3/8): Tx IDLE May 19 10:46:23.483: neat msg at slot 0: (3/8): Rx BLOCKED May 19 10:46:23.827: neat msg at slot 0: (3/8): Wait for IDLE May 19 10:46:23.979: neat msg at slot 0: (3/8): Rx IDLE

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R2 Analog Line signalling condition

State of the circuit

Forward

Presentation_ID

Backward

1. Idle

Tone-on

Tone-on

2. Seized

Tone-off

Tone-on

3. Answered

Tone-off

Tone-off

4. Clear-back

Tone-off

Tone-on

5. Release

Tone-on

Tone-on or off

6. Blocked

Tone-on

Tone-off

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Example Analog Signalling

May 19 11:01:09.719: neat msg at slot 0: (3/6): Rx Tone-off May 19 11:01:18.939: neat msg at slot 0: (3/6): Tx Tone-off ... May 19 11:02:14.879: neat msg at slot 0: (3/6): Tx Tone-on May 19 11:02:16.851: neat msg at slot 0: (3/6): Rx Tone-on

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Inter Signalling • Inter Signalling (Call Setup Control Signals) The handshaking between two offices to collect digits for the terminating office to complete/route the call to the destination phone number In-band in each timeslot Multi-Frequency Signalling (some countries use DTMF instead) Presentation_ID

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Inter Signalling • The MF signals used during the inter signalling are divided in forward signal groups (Group-I, Group-II) and backward signal groups (Group A, Group B) • Inter signalling starts after the “Seize-Ack” line signal

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Inter Signalling

• Most country-specific variations to R2 are seen in the inter signalling

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Multi Frequency Combinations

No.

Presentation_ID

Frequencies (Hz) Forward direction (signals of Groups I and II)

1380

1500

1620

1740

1860

1980

Numeral value =

Backward direction (signals of Groups A and B)

1140

1020

900

780

660

540

x+y

Index (x)

f0

f1

f2

f3

f4

f5

Weight (y)

0

1

2

4

7

11

y

1

0+1

x

2

0+2

x

3

1+2

4

0+4

5

1+4

6

2+4

7

0+7

8

1+7

9

2+7

10

3+7

11

0 + 11

12

1 + 11

13

2 + 11

14

3 + 11

15

4 + 11

y x

y

x

y x

y x

y

x

y x

y x

y x

y

x

y x

y x

y x

y x

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y

22

Group I Forward Signals

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Group II Forward Signals Group II forward signals

Presentation_ID

Combination (a)

Designation of the signal (b)

Meaning of the signal (c)

1 2 3 4 5 6

II-1 II-2 II-3 II-4 II-5 II-6

Subscriber without priority Subscriber with priority Maintenance equipment Spare Operator Data transmission

7 8 9 10

II-7 II-8 II-9 II-10

Subscriber (or operator without forward transfer facility) Data transmission Subscriber with priority Operator with forward transfer facility

11 12 13 14 15

II-11 II-12 II-13 II-14 II-15

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Remarks (d)

24

Group A Backward Signals Group A backward signals

Combination (a)

1 2 3 4 5 6 7 8

Presentation_ID

Designation of the signal (b)

A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8

Meaning of the signal (c)

Send next digit (n + 1) Send last but one digit (n -1) Address-complete, changeover to reception of Group B signals Congestion in the national network Send calling party's category Address-complete, charge, set-up speech conditions Send last but two digit (n - 2) Send last but three digit (n - 3)

9 10

A-9 A-10

11 12 13 14

A-11 A-12 A-13 A-14

Send country code indicator Send language or discrimination digit Send nature of circuit Request for information on use of an echo suppressor (is an incoming half-echo suppressor required ?)

15

A-15

Congestion in an international exchange or at its output

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Group B Backward Signals

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Inter Signalling • The same MF tones get different meanings, i.e. switched between different groups, during the interaction • This change between groups are triggered by specific MF tones

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Inter Signalling

yoghourt(config-controller)#cas-group 0 timeslots 1-31 type r2-digital ? dtmf DTMF tone signalling r2-compelled R2 Compelled Signalling r2-non-compelled R2 Non Compelled Signalling r2-semi-compelled R2 Semi Compelled Signalling

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Inter Signalling

• Inter signalling can be done in different ways: Compelled Semi-compelled Non-compelled

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Inter Signalling • Compelled: When a tone-pair is sent from the switch, the tones stay on until the converter responds/acks back with a tone-pair, that signals the switch to turn the tones off, ... So the tones are 'compelled' to stay on until we tell them to turn off

• Semi-compelled: Forward tone-pairs are sent as compelled (from switch to router). The backward tones (from router to switch) are sent as pulses Presentation_ID

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Inter Signalling • Non-compelled: The tone-pairs are sent as pulses, i.e. they stay on for a short duration, and the response back to the switch is sent as pulses

• A reason not to use compelled signalling is on slow (satellite) links, in case of compelled the call setup would be very long Presentation_ID

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31

Compelled Outgoing

Incoming

Forward signal Acknowledging backward signal Time

Next forward signal Acknowledging backward signal

Sending

Presentation_ID

Receiving

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Example Compelled Switch DNIS digit “3”

DNIS digit “2”

DNIS digit “1”

Normal subscriber

Presentation_ID

I-3→ I-2→ I-1→

II-1→

as5x00 ←A-1 Send next digit ←A-1 Send next digit ←A-1 Send next digit timeout 3 sec ←A-3 Address complete ←B-6 Subscriber’s line free, charge

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Semi-Compelled Outgoing

Incoming

Forward signal Acknowledging backward signal Time

Next forward signal Acknowledging backward signal

Sending

Presentation_ID

Receiving

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Example Semi-Compelled Switch DNIS: 321

I-3→ I-2→ I-1→

II-1→

Presentation_ID

as5x00 ←A-1 (Pulse) ←A-1 (Pulse) ←A-1 (Pulse) timeout 3 sec ←A-3 (Pulse) ←B-6 (Pulse)

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Non-Compelled Outgoing

Incoming

Forward signal

Time

Next forward signal

Sending

Presentation_ID

Receiving

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Example Non-Compelled Switch DNIS: 321

as5x00

I-3→ I-2→ I-1→ timeout 3 sec ←B-6

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Example - Digital Compelled Switch Seize→ → I-3→ → I-2→ → I-1→ →

as5x00 ←Seize_Ack ←A-1 ←A-1

• Line signalling (Timeslot 16)

•

Inter signalling (In-band)

←A-1 timeout 3 sec

II-1→ →

Presentation_ID

←A-3

←B-6 ←Answer Cisco Systems Confidential

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Custom Configurations yoghourt(config-controller)#cas-custom 0 yoghourt(config-ctrl-cas)#? CAS custom commands: answer-signal Answer signal to be used caller-digits Digits to be collected before requesting CallerID category Category signal country Country Name default Set a command to its defaults dnis-digits Expected number of DNIS digits exit Exit from cas custom mode invert-abcd invert the ABCD bits before tx and after rx ka KA Signal kd KD Signal metering R2 network is sending metering signal nc-congestion Non Compelled Congestion signal no Negate a command or set its defaults unused-abcd Unused ABCD bit values Presentation_ID

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Dnis-digits • Expected number of DNIS digits • If the as5x00 doesn’t know the number of DNIS digits beforehand, it has to rely on a timeout mechanism (3 seconds) to detect the end of DNIS • Configuring this will speed up the connect time with 3 seconds since the number of DNIS digits is known beforehand

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Dnis-digits DNIS: 321 dnis-digits 3

Switch First DNIS digit I-3→ Second DNIS digit I-2→ Third DNIS digit I-1→ NO 3 second timeout! II-1→

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as5x00 ←A-1 ←A-1 ←A-3 ←B-6

42

Request ANI • ANI is CallerID • DNIS is always sent, ANI can only be sent if the line is provisioned for it • Usually (always?) the first ANI digit is the Caller Category • By default, ANI will be requested after reception of first DNIS digit

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Request ANI DNIS: 321 ANI: 456

Switch First DNIS digit I-3→ Caller Category I-1→ First ANI digit I-4→ I-5→ I-6→ End of ANI digits I-15→ Second DNIS digit I-2→ I-1→

II-1→ Presentation_ID

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as5x00 ←A-5 ←A-5 ←A-5 ←A-5 ←A-5 ←A-1 ←A-1 ←A-1 timeout 3 sec ←A-3 ←B-6 44

Caller-digits

• Specifies the number of digits the access server needs to collect before it requests ANI information. Default is 1, which is the ITU default

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Caller-digits DNIS: 321 ANI: 456 caller-digits 2

Switch First DNIS digit I-3→ Second DNIS digit I-2→ Caller Category I-1→ First ANI digit I-4→ Second ANI digit I-5→ Third ANI digit I-6→ End of ANI digits I-15→ Third DNIS digit I-1→

II-1→ Presentation_ID

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as5x00 ←A-1 ←A-5 ←A-5 ←A-5 ←A-5 ←A-5 ←A-1 ←A-1 timeout 3 sec ←A-3 ←B-6 46

Answer-signal • Answer signal to be used. This is the last signal to be sent from the as5x00 to the switch to signal that the signalling is complete. You can specify the group A signal or the group B signal. Default is group-b 6, which is the ITU default. • Configuring a group-a signal has as effect that the “II-1; B-6” sequence doesn’t take place (I think because of CSCdj42960) Presentation_ID

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Answer-signal DNIS: 321 answer-signal group-a 6

Switch First DNIS digit I-3→ Second DNIS digit I-2→ Third DNIS digit I-1→

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as5x00 ←A-1 ←A-1 ←A-1 timeout 3 sec ←A-6

48

Answer-signal DNIS: 321 answer-signal group-b 8

Switch First DNIS digit I-3→ Second DNIS digit I-2→ Third DNIS digit I-1→

II-1→

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as5x00 ←A-1 ←A-1 ←A-1 timeout 3 sec ←A-3 ←B-8

49

Category

• Specifies the type of incoming call (E.g. Subscriber with priority, Normal subscriber). Default is 1 (Normal subscriber), which is the ITU default.

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Category DNIS: 321 category 2

Switch First DNIS digit I-3→ Second DNIS digit I-2→ Third DNIS digit I-1→

II-2→

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as5x00 ←A-1 ←A-1 ←A-1 timeout 3 sec ←A-3 ←B-6

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Debugging • Inter signalling: debug modem csm • Line signalling: modem-mgmt csm debug-rbs (Note: You need to configure “service internal”)

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Debugging Example Jun 3 15:02:53.947: neat msg at slot 0: (3/0): Rx SEIZURE (ABCD=0001) ---> receiving SEIZURE Jun 3 15:02:53.991: VDEV_ALLOCATE: slot 1 and port 0 is allocated. ---> allocate modem 1/0 to receive MF tones Jun 3 15:02:53.991: CSM_RX_CAS_EVENT_FROM_NEAT:(0000): EVENT_CALL_DIAL_IN at slot 1 and port 0 Jun 3 15:02:53.991: CSM_PROC_IDLE: CSM_EVENT_DSX0_CALL at slot 1, port 0 Jun 3 15:02:53.991: Mica Modem(1/0): Configure(0x0) Jun 3 15:02:53.991: Mica Modem(1/0): Configure(0x3) Jun 3 15:02:53.991: Mica Modem(1/0): Call Setup Jun 3 15:02:54.091: neat msg at slot 0: (3/0): Tx SEIZURE_ACK (ABCD=1101) ---> transmit SEIZURE_ACK Jun 3 15:02:54.103: Mica Modem(1/0): State Transition to Call Setup Jun 3 15:02:54.103: Mica Modem(1/0): Went offhook Jun 3 15:02:54.103: CSM_PROC_IC1_RING: CSM_EVENT_MODEM_OFFHOOK at slot 1, port 0 Jun 3 15:02:54.103: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_IDLE Jun 3 15:02:54.403: Mica Modem(1/0): Rcvd Digit detected(9) ---> received MF tone I-9 Jun 3 15:02:54.403: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COLLECT_DNIS Jun 3 15:02:54.403: Mica Modem(1/0): Generate digits:called_party_num=1 len=1 ---> transmit MF tone A-1 (next digit) Jun 3 15:02:54.523: Mica Modem(1/0): Rcvd Digits Generated Jun 3 15:02:54.583: Mica Modem(1/0): Rcvd Digit detected(#) Jun 3 15:02:54.583: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COLLECT_DNIS Jun 3 15:02:54.583: Mica Modem(1/0): Generate digits:called_party_num=# len=1

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Debugging Example Jun 3 15:02:56.267: Mica Modem(1/0): Rcvd Digit detected(5) Jun 3 15:02:56.267: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COLLECT_DNIS Jun 3 15:02:56.267: Mica Modem(1/0): Generate digits:called_party_num=1 len=1 Jun 3 15:02:56.387: Mica Modem(1/0): Rcvd Digits Generated Jun 3 15:02:56.507: Mica Modem(1/0): Rcvd Digit detected(#) Jun 3 15:02:56.507: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COLLECT_DNIS Jun 3 15:02:56.507: Mica Modem(1/0): Generate digits:called_party_num=# len=1 Jun 3 15:02:56.623: Mica Modem(1/0): Rcvd Digits Generated ---> 3 second timeout after last DNIS digit Jun 3 15:02:59.267: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COLLECT_DNIS Jun 3 15:02:59.267: Mica Modem(1/0): Generate digits:called_party_num=3# len=2 ---> transmit pulsed A-3 (Address complete, change to B-signal) Jun 3 15:02:59.455: Mica Modem(1/0): Rcvd Digits Generated Jun 3 15:02:59.635: Mica Modem(1/0): Rcvd Digit detected(1) ---> receive II-1 (normal subscriber) Jun 3 15:02:59.635: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_CATEGORY Jun 3 15:02:59.635: Mica Modem(1/0): Generate digits:called_party_num=6 len=1 ---> transmit B-6 (subscriber’s line free, charge) Jun 3 15:02:59.755: Mica Modem(1/0): Rcvd Digits Generated Jun 3 15:02:59.875: Mica Modem(1/0): Rcvd Digit detected(#) Jun 3 15:02:59.875: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_COMPLETE Jun 3 15:02:59.875: Mica Modem(1/0): Generate digits:called_party_num=# len=1 Jun 3 15:02:59.995: Mica Modem(1/0): Rcvd Digits Generated

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Debugging Example Jun Jun

3 15:03:00.875: R2 Incoming Modem(1/0): DSX (0/3/0): STATE: R2_IN_WAIT_GUARD 3 15:03:00.875: CSM_PROC_IC2_COLLECT_ADDR_INFO: CSM_EVENT_ADDR_INFO_COLLECTED (DNIS=98765, ANI=) at slot 1, port 0

Jun

3 15:03:01.175: slot 1 and port 0 Jun 3 15:03:01.175: port 0 Jun 3 15:03:01.175: Jun 3 15:03:01.179: ---> transmit ANSWERED Jun 3 15:03:01.267: Jun 3 15:03:06.395: Jun 3 15:03:15.459: Jun 3 15:03:17.091: Jun 3 15:03:17.327: yoghourt# yoghourt#! Connected

Presentation_ID

CSM_RX_CAS_EVENT_FROM_NEAT:(0000):

EVENT_CHANNEL_CONNECTED at

CSM_PROC_IC4_WAIT_FOR_CARRIER: CSM_EVENT_DSX0_CONNECTED at slot 1, Mica Modem(1/0): Link Initiate neat msg at slot 0: (3/0): Tx ANSWERED (ABCD=0101) Mica Mica Mica Mica Mica

Modem(1/0): Modem(1/0): Modem(1/0): Modem(1/0): Modem(1/0):

State State State State State

Transition Transition Transition Transition Transition

to to to to to

Connect Link Trainup EC Negotiating Steady State

....

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Debugging Example

yoghourt#! Connected yoghourt# yoghourt# yoghourt# ---> disconnecting call Jun 3 15:09:18.783: Jun 3 15:09:21.379: Jun 3 15:09:21.379: Jun 3 15:09:21.379: 0 Jun 3 15:09:21.379: Jun Jun Jun

Presentation_ID

....

Mica Modem(1/0): State Transition to Terminating Mica Modem(1/0): State Transition to Idle Mica Modem(1/0): Went onhook CSM_PROC_IC5_OC6_CONNECTED: CSM_EVENT_MODEM_ONHOOK at slot 1, port VDEV_DEALLOCATE: slot 1 and port 0 is deallocated

3 15:09:21.379: neat msg at slot 0: (3/0): Tx BWD_CLEAR (ABCD=1101) 3 15:09:28.491: neat msg at slot 0: (3/0): Rx IDLE (ABCD=1001) 3 15:09:30.519: neat msg at slot 0: (3/0): Tx IDLE (ABCD=1001)

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