© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Cisco IP Communications PSTN and PBX Integrations Implementing BRI and PRI Trunks

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v BRI and PRI Interfaces BRIT1 PRIE1 PRI B-Channels2 x 64 kbps23 x 64 kbps30 x 64 kbps D-Channels1 x 16 kbps1 x 64 kbps Framing16 kbps8 kbps64 kbps Total Data Rate160 kbps1.544 Mbps2.048 Mbps FramingNT, TE FrameSF, ESFMultiframe Line Coding2B1Q or 4B3TAMI or B8ZSHDB3 CountryWorldNorth America, JapanEurope, Australia

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v BRI and PRI Interfaces (Cont.) Voice, video, and data sent over separate B channels Known as Common Channel Signaling (CCS): –Signaling data is sent over a single D channel used by all B channels. Drop and insert: –B channels can be statically multiplexed between interfaces.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v PSTN BRI and PRI Interfaces (Cont.) PBX T1 connection to ISP 23 B channels Connection to PBX 21 B channels BRI connection to Access Server 2 B channels Channels split up Access Gateway ISDN Drop and Insert

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces Q.921 Link Access Procedure, D Channel Protocol (LAPD) similar to HDLC Layer 2 ISDN Signaling Protocol Terminal Endpoint Identifier (TEI) identifies end devices –Layer 2 address –Statically configured at the end device or dynamically allocated by the PSTN

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) Q.931 Layer 3 ISDN signaling protocol Supports these connections: –User-to-user –Circuit-switched –Packet-switched Various call-establishment, call-termination, information, and miscellaneous messages

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v PSTN Signaling for BRI and PRI Interfaces (Cont.) PSTN A PBX is connected to the PSTN on the network side. The voice gateway provides a network side emulation. N U Network side User side N U PSTN In toll bypass, the PBX may provide network side emulation to the voice gateway. IP WAN U PSTN N UN U N IP WAN U N U

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) Protocol discriminator 0000Length of reference call value Flag 0 IEs as required The general structure of the ISDN frame: Call reference value Message type

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) 000 Call Establishment001 Call Information ALERTing CALL PROCeeding PROGress SETUP CONNect SETUP ACKnowledge CONNect ACKnowledge USER INFOrmation SUSPend REJect RESume REJect SUSPend RESume SUSPend ACKnowledge RESume ACKnowledge 010 Call Clearing011 Miscellaneous DISConnect Restart RELease Restart ACKnowledge RELease COMplete SEGment FACility NOTIFY STATUS ENQuiry Congestion Control INFOrmation STATUS

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Setup Acknowledged Connect Alerting Signaling for BRI and PRI Interfaces (Cont.) Calling Party Called Party ISDN Switch Setup Call Proceeding Call Proceeding Additional Info Connect Acknowledge Connect Alerting Ring Back Ring ISDN Service Provider Q.931 Signaling SS7 Signaling Connect Acknowledge

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) Protocol discriminator 0000Length of CRV FlagCRV 0Message type IEs as required The ISDN Protocol Stack Octet IE identifier 2Length of IEs 31Coding standard0Location 41IEs (multiple bytes) Typical format of a variable-length IE:

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) Cause IE (0x08) Length of the Cause Information 1Coding Standard 0Location 1ClassValue The cause IE for diagnosing call failure Facility IE (0x1C) Length of the Facility Information 1Coding Standard 0Location 1Facility Description The facility IE for the caller name in QSIG: Progress IE (0x1E) Length of the Progress Information 1Coding Standard 0Location 1Progress Description The progress IE for tones and prompts Display IE (0x28) Length of the Display Information 1Coding Standard 0Location 1Display Description The display IE for the caller name in Q.931

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) *Mar 27 15:11:40.472: ISDN Se0/0:23 Q931: TX -> SETUP pd = 8 callref = 0x0006 Bearer Capability i = 0x8090 Standard = CCITT Transer Capability = Speech Transfer Mode = Circuit Transfer Rate = 64 kbit/s Channel ID i = 0xA98397 Exclusive, Channel 23 Calling Party Number i = 0x2181, 'XXXXXXXXXX' Plan:ISDN, Type:National Called Party Number i = 0x80, 'XXXXXXXXXXX' Plan:Unknown, Type:Unknown *Mar 27 15:11:40.556: ISDN Se0/0:23 Q931: RX

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Signaling for BRI and PRI Interfaces (Cont.) Non-Facility Associated Signaling Allows a single D channel to control multiple PRI interfaces. A backup D channel can be configured, but only the NFAS primary D channel must be configured. NFAS is only supported with a channelized T1 controller. The router must connect to a 4ESS, DMS250, DMS100, or a national ISDN switch type. D channel 64 kbps (signaling) 23 B channels (voice) ISDN T1 PRI D channel 64 kbps (signaling) 23 B channels (voice) ISDN T1 PRI NFAS 24 B channels (voice)

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v isdn switch-type {country specific switch-type} router(config)# Defines the telephone company switch type interface {bri | pri} interface number router(config)# Enters interface configuration mode isdn overlap-receiving router(config-if)# Activates ISDN protocol overlap signaling BRI and PRI Configuration Commands

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v isdn {spid1 | spid2} spid-number router(config-if)# For BRI Defines an ISDN Service Profile Identifier (SPID) Necessary for some service providers isdn incoming-voice voice router(config-if)# Configures the port for incoming voice calls BRI and PRI Configuration Commands (Cont.) pri-group timeslots timeslot-range [nfas_d {backup | none | primary {nfas_int number | nfas_group number | rlm-group number}} | service] router(config-controller)# Configures the logical voice ports on a T1/E1 controller

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v network-clock-participate {aim | slot | wic} slot number router(config-if)# Specifies which clock source to use for DSP clocking isdn protocol-emulate {user | network} router(config-if)# Defines Layer 2 and Layer 3 user-side or network-side emulation BRI and PRI Configuration Commands (Cont.)

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v isdn static-tei tei-number router(config-if)# Configures a static ISDN Layer 2 address (BRI only) clear interface slot|port router(config)# Resets the specified ISDN interface Required after TEI configuration change BRI and PRI Configuration Commands (Cont.) isdn point-to-point-setup router(config-if)# Configures a point-to-point ISDN

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring BRI Trunks Phone Phone Munich Router1 ISDN BRI 2 B channels + 1 D channel PSTN

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring BRI Trunks (Cont.) Perform the following steps to build an ISDN BRI trunk to the PSTN: 1. Configure the ISDN switch type. 2. Configure DSP clocking. 3. Configure ISDN overlap-receiving. 4. Configure incoming ISDN calls as voice. 5. Configure BRI as user-side. 6. Reset the interface.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring BRI Trunks (Cont.) router#clear interface bri0/0 ! network-clock-participate wic 0 ! interface bri 0/0 isdn switch-type basic-net3 isdn overlap-receiving isdn incoming-voice voice isdn protocol-emulate user !

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring PRI Trunks Phone Phone Munich Router1 ISDN PRI 30 B channels + 1 D channel PSTN Switchboard -0

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring PRI Trunks (Cont.) Perform the following steps to build an ISDN PRI trunk to the PSTN: 1. Configure the ISDN switch type. 2. Configure DSP clocking. 3. Configure the E1 line code. 4. Configure the E1 frame format. 5. Configure the clock source. 6. Configure a logical voice port. 7. Configure ISDN overlap-receiving. 8. Configure incoming ISDN calls as voice. 9. Reset the interface.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Configuring PRI Trunks (Cont.) router# clear interface s0/0/0:15 ! network-clock-participate wic 0 ! isdn switch-type primary-net5 ! interface Serial0/0/0:15 isdn switch-type primary-net5 isdn overlap-receiving isdn incoming-voice voice !

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks System clocking Signaling mismatch Switch type mismatch Numbering type and plan mismatches No ringback No busy tone on outbound VoIP calls ISDN timer issues

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v How to Troubleshoot a No-Ringback Situation Situation: No ringback tone on VoIP toll-bypass calls: –Symptom: POTS (PSTN/PBX) user places a call (through Cisco router or gateways) and does not hear a ringback tone before the call is answered. Solution 1: Use the voice call send alert command in global configuration mode. Solution 2: Configure progress_ind alert enable 8. Situation: No ringback tone on VoIP inbound calls to Cisco Unified CallManager or third-party VoIP devices through Cisco IOS gateway: –Symptom: POTS (PSTN/PBX) user places a call to an IP phone through a Cisco router or gateway and does not hear a ringback tone before the call is answered. –Solution: Configure progress_ind setup enable 3 under the VoIP dial peer configuration.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v How to Troubleshoot a No-Ringback Situation (Cont.) Situation: No ringback tone on VoIP outbound calls from Cisco Unified CallManager or third-party VoIP devices through Cisco IOS gateway: –Symptom: User places a call from IP phone or third-party device to an outside number through a Cisco router or gateway and does not hear a ringback tone. Solution 1: Configure progress_ind alert enable 8 under the outgoing POTS dial peer configuration. Solution 2: Additionally configure progress_ind setup enable 3.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks (Cont.) Troubleshoot a No-Ringback Situation (Cont.) No ringback tone when call is transferred from Cisco Unified CallManager or Cisco Unity voice mail: –Symptom: An incoming call from a Cisco gateway or router to Cisco Unified CallManager or Cisco Unity voice mail that is transferred after the call is answered does not hear ringback. Solution: Configure the gateway as an MGCP Gateway instead of H.323.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks (Cont.) show controllers interface-name interface-number router# Displays Layer 1 information show isdn status router# Validates Layer 1 and Layer 2 debug isdn events router# Displays ISDN events occurring on the user side of the ISDN interface

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks (Cont.) debug isdn q921 router# Displays ISDN Q.921 (layer 2) debug information debug isdn q931 router# Displays information about call setup and teardown of Layer 3 ISDN network connections between the local router (user-side) and the network

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks (Cont.) Calling Party Number i = 0x2080, ' ' Plan:Unknown, Type:National Called Party Number i = 0xA1, ' ' Plan:ISDN, Type:National *Jul 4 15:13:18.099: ISDN Se0/0/0:23 Q931: RX

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Verifying BRI and PRI Trunks (Cont.) *Mar 20 21:07:45.025: ISDN BR0: Event: Call to at 64 Kb/s *Mar 20 21:07:45.033: ISDN BR0: TX -> SETUP pd = 8 callref = 0x2C *Mar 20 21:07:45.037: Bearer Capability i = 0x8890 *Mar 20 21:07:45.041: Channel ID i = 0x83 *Mar 20 21:07:45.041: Keypad Facility i = 0x *Mar 20 21:07:45.141: ISDN BR0: RX

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Summary ISDN service is provided as 192-kbps 2B+D BRI trunks, Mbps 23B+D T1 PRI trunks, or Mbps 30B+D E1 PRI trunks. Some PBXs are unable to behave as terminal equipment and will only communicate to the voice gateway when a BRI network-side interface is configured on the gateway. The Layer 3 Q.931 frame contains messages such as ALERTING, SETUP, and CONNECT. These messages are supported in carrying out their function by IEs such as FACILITY, DISPLAY, PROGRESS, and CAUSE. Facility IEs are for supplemental services. Display IEs include caller name and other display information.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v Summary (Cont.) Common issues with ISDN circuits include system clocking, signaling mismatch, switch mismatch, numbering plan, and ISDN timer. Care must be taken to ensure that PBX requirements for the network- and user-side are met for trunk configuration with any of the Cisco voice gateways. Cisco Unified CallManager trace messages, the Q.931 translator, and cause IEs are the diagnostic tools that can help system administrators isolate BRI or PRI problems in their networks.

© 2006 Cisco Systems, Inc. All rights reserved.GWGK v