© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Configuring PSTN Interfaces and Voice Dial Peers ITU Supplementary Services

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Outline Overview H.450. x Series Protocols Call Transfer Using H Call Forwarding Using H Issues and Workarounds for H.450. x Protocols Summary

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Protocols in the H.450. x Series H General *H Transfer *H Forwarding H Call Hold H Call Park H Call Waiting H MWI H Name Identification H Callback H Camp On H Barge *H Capabilities * Supported in Cisco CallManager Express 3.1

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Transfer A B A B C A B C A B C A B C A B C A calls B. B wants to transfer to C and places consultation call. B and C talk. B commits transfer. B requests and receives an H consultation-ID from C. B sends transfer request to A with consultation-ID. A calls C, including the consultation-ID in the call setup message. As call to C is successful. A and C disconnect calls to B.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Transfer Advantages Final A-to-C call path is optimal, with no hair-pin media or control path, for example: –New York calls Los Angeles and is transferred to London. Final call is direct from New York to London (not via Los Angeles). Call parameters for A-B, B-C, and A-C can all be different (e.g., different codecs). After the transfer is committed, all resources at B are released; H is very scalable. There is no H limit to the number of times a call can be transferred.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Transfer Disadvantages All voice gateway routers in the network must support H Calls may drop and transfers will not complete correctly if participating endpoints do not support H H is used even when the transferee is on the same Cisco CallManager Express system as the transferor; the transferee must still support H

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v supplementary-service h CMERouter(config-voi-serv)# Enables H globally for calls transferred to the system (enabled by default) supplementary-service h CMERouter(config-dial-peer)# Enables H on a dial peer for calls transferred to the system (overrides the system level command) H Transfer Commands voice service voip CMERouter(config)# Enters voice service mode

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v transfer-system full-consult {blind | full-blind | full consult | local} CMERouter(config-telephony-service)# Sets the system transfer mechanism transfer-pattern pattern CMERouter(config-telephony-service)# Enables transfers to non–ephone-dn destinations H Transfer Commands (Cont.)

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Example: H Transfer H is turned on by default in Cisco CallManager Express 3.1, for calls transferred to the system. H must be enabled for initiating transfers within the system. voice service voip supplementary-service h dial-peer voice 1 voip destination-pattern 3... no supplementary-service h session target ipv4: telephony-service transfer-system full-consult transfer-pattern 3... A default setting that enables H globally for transferred parties Dial-peer setting overrides the global setting for transferred parties Enables the system to initiate transfers and specifies the type of transfer Specifies which non–ephone-dn destinations that calls can be transferred to

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Forwarding A B A B C A B C A B C A B C A calls B. B wants to forward As call to C. B sends forward request to A. A calls C. As call to C is successful. A disconnects call attempt to B.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Advantages The final A-to-C call path is optimal, with no hair-pin media or control path, for example: –New York calls Los Angeles and is forwarded to London. Final call is direct from New York to London (not via Los Angeles). Call parameters for A-B and A-C can be different (e.g., different codecs). After forwarding is done, all resources at B are released; H is very scalable. There is no H limit to the number of times a call can be forwarded.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Disadvantages All voice gateway routers in the network must support H Calls may drop if participating endpoints do not support H H is used even when the transferee is on the same Cisco CallManager Express system as the phone that requests the forwarding. The transferee must still support H

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v supplemental-service h CMERouter(config-voi-serv)# Enables H globally (enabled by default) supplemental-service h CMERouter(config-dial-peer)# Enables H on a dial peer H Forward Commands Dial peer setting overrides the global voice service setting voice service voip CMERouter(config)# Enters voice service mode

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v call-forward pattern pattern CMERouter(config-telephony-service)# Enables forwarding to non–ephone-dn destinations H Forward Commands (Cont.)

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Example: H Forwarding H is turned on by default for forwards to the system. H must be enabled for forwards initiated within the system. voice service voip supplemental-service h dial-peer voice 1 voip destination-pattern 3... no supplemental-service h session target ipv4: telephony-service call-forward pattern 3... A default setting that enables H globally for forwarded parties Dial-peer setting overrides the global setting for forwarded parties Specifies which non-ephone-dn destinations that calls can be forwarded to.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v H Capabilities Cisco CallManager Express 3.1 adds H support. H provides a supplementary services indication capabilities exchange. H allows dynamic auto detection of non-H.450.x-capable endpoints. H indications are provided on Setup, Proceeding, Alerting and Connect messages. H allows the Cisco CallManager Express 3.1 system to explicitly detect if H and H are supported on a call-by-call basis. If H and H is not supported, Cisco CallManager Express 3.1 can fall back to providing hairpin VoIP-to-VoIP call routing (for H.323). Previous versions of Cisco CallManager Express support H and H but not H

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Using H When you turn on the H service, H and H are disabled unless a positive H indication is received from all the other VoIP endpoints involved in the call. H is turned off by default to minimize risk of compatibility issues with third-party H.323 systems.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v supplementary-service h [advertise-only] CMERouter(config-voi-serv)# Enables H (disabled by default) H Commands voice service voip CMERouter(config)# Enters voice service mode

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Issues and Workarounds CallManager does not support H.450. x protocols. VoIP-to-VoIP hairpin call routing can be inefficient and bandwidth-intensive. A mixed Cisco CallManager Express mixed 3.0 and 3.1 environment presents special considerations. Upgrading Cisco CallManager Express 3.0 to 3.1 presents migrating issues.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Detecting CallManager CallManager does not support H.450.2, H.450.3, or H A proprietary detection mechanism is used. –CallManager sends a nonstandard identifier in most of its H.225 messages. This tells you that H.450. x can not be supported for the call. –This is useful if you have both CallManager and older Cisco CallManager Express 3.0 systems in the same network and, therefore, cannot use H

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v VoIP-to-VoIP Hairpin Calls When H.450. x protocols are not supported, a VoIP-to-VoIP hairpin may be used. This can cause call routing efficiency issues. Inefficient bandwidth consumption may occur on WAN links. This is explicitly enabled and is disabled by default. Hairpinning, when enabled, will be used if one of the following conditions are met: –H is used to detect that H.450.2/3 is not supported by remote VoIP system. –H and H are explicitly disabled. –Cisco CallManager Express 3.1 auto-detects that the remote system is a CallManager.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v allow-connections h323 to h323 CMERouter(config-voi-serv)# Enables the VoIP-to-VoIP hairpinning of forwards and transfers Enabling VoIP-to-VoIP Hairpin Calls voice service voip CMERouter(config)# Enters voice service mode

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v CallManager Express A IP WAN Step 1 - Call from 1000 to 2000 Step 2 - Transfer or forward to 3000 voice service voip allow-connections h323 to h Step 3 – Call is hairpinned and connected to 3000 Non-H.450 Gateway Example: VoIP-to-VoIP Hairpin Call CallManager Express B

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Using Cisco CallManager Express 3.1 with 3.0 Turn on H in advertise-only mode. –The router sends out H indications for the benefit of remote VoIP endpoints. –Cisco CallManager Express does not require a H response and has H and H enabled for all calls in this mode. –This is intended to assist with Cisco CallManager Express 3.0 to Cisco CallManager Express 3.1 network upgrades. –Cisco CallManager Express 3.1 can still auto-detect a CallManager in this mode. Both the Cisco CallManager Express 3.1 and Cisco CallManager Express 3.0 assume that H and H can be used for all calls. If detected, CallManager is auto-detected by Cisco CallManager Express and may use hairpinning if enabled.

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Upgrading Cisco CallManager Express 3.0 to 3.1 As each new Cisco CallManager Express 3.1 is installed, turn on H in advertise-only mode. –supplementary-service h advertise only When all Cisco CallManager Express 3.0 systems in the network have been upgraded to CallManager Express 3.1: –remove the advertise-only restriction –supplementary-service h

© 2005 Cisco Systems, Inc. All rights reserved. IPTX v Summary H is used to efficiently transfer calls from one H device to another. H is used to forward calls efficiently from one H device to another. H is used to detect whether a device supports H or H Cisco CallManager Express 3.1 supports H.450.2, H.450.3, and H H transfer and H forward are enabled by default for transferred and forwarded calls that arrive at Cisco CallManager Express 3.1. Support for initiating an H transfer or H forward must be enabled on the Cisco CallManager Express router. When H.450. x protocols are disabled or not supported, a VoIP-to-VoIP hairpin may be used. This ability is disabled by default. CallManager, which does not support H.450. x protocols, can be automatically detected by Cisco CallManager Express. When upgrading Cisco CME 3.0 to 3.1, enable H with advertise-only mode until all the Cisco CallManager Express routers have been upgraded to 3.1.