Cisco Systems H.323 appendix 38 Fax, HSI Information Message Support

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Chapter 3 Provisioning the Cisco HSI

HSI Feature Configuration

Refer to Cisco PGW and Cisco IOS documentation at www.cisco.com for further information on these commands.

T.38 Fax

The T.38 Fax feature enables the HSI to alter a call, initially established for voice, to support a fax transmission.

When a fax call is initiated, a voice call is established. When the terminating gateway detects the fax tone generated by the terminating fax machine, the gateway initiates a T.38 mode request using H.245 procedures from the terminating gateway. If the opposite end of the call acknowledges the T.38 mode request, the initial audio channel is closed and a T.38 fax relay channel is opened.

You enable T.38 Fax for the HSI by specifying static system data parameters. By default, T.38 is provisioned on the HSI by use of the following commands:

prov-add:name=sys_config_static,t38maxval="MaxBit 0x90, FxMaxBuf 0xc8, FxMaxData 0x48" prov-add:name=sys_config_static,t38options="FxFillBit 0, FxTransMMR 0, FxTransJBIG 0, FxRate Trans, FxUdpEC Red"

Table 3-3describes the T.38 static system data parameters. The T.38 parameters for HSI correspond to T.38 parameters proposed in the ITU T.38 recommendation.

Configuring T.38 Fax on the Cisco PSTN Gateway

To enable T.38 Fax throughout the system, you must enable T.38 Fax on the Cisco PGW. On the PGW,

T.38 is enabled through a trunk group property by use of the following MML command:

prov-add:trnkgrpprop:name="2000",FaxSupport="1"

Configuring T.38 Fax on a Cisco IOS H.323 Gateway

Enable T.38 Fax on a Cisco IOS H.323 gateway by issuing the following IOS commands:

voice service voip

fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none

Configuring T.38 Fax on a Cisco IOS MGCP Gateway

Enable T.38 fax on a Cisco IOS MGCP gateway by issuing the following IOS commands:

voice service voip

fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none

mgcp package-capability fxr-package

Refer to PGW and Cisco IOS documentation at www.cisco.com for further information on these commands.

HSI INFORMATION Message Support

Cisco CallManager uses the H.225 INFORMATION message during transfer to indicate that ringback tone is on or off. The Cisco HSI now supports this message to correctly interoperate with Cisco CallManager.

 

Cisco H.323 Signaling Interface User Guide

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OL-4806-01 Rev. A14

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Contents Provisioning the Cisco HSI MML Configuration Commands CommandCommand Description DescriptionIntroduction to MML Command Operation for HSI Initiating an MML Session to Enable Dtmf on the HSIVerifying the Configuration System Configuration Data Reverting to the Base ConfigurationStatic System Data ExampleParameter Type Description Parameter, set it to Enabled Issue the command restart-softwconfirm Changing Static System DataParameter Description Default Dynamic System DataOVLDLEVEL1PERCENT OVLDLEVEL3PERCENTOVLDLEVEL1FILTER OVLDLEVEL1THRESHLOWERAlarmdebouncetime OVLDLEVEL3FILTEROVLDLEVEL3THRESHLOWER OVLDLEVEL3THRESHUPPERNonprovisionable Data MML Provisionable DataSystem Parameters ParametersParameter Name Description Type Example Update Type NullRAS Parameters Parameter Name Description Type ExampleAllowCallsWhenNonReg If this parameter is present, it String H323ESP Update Parameter Name TypeINTEGER0,1 Codec Selection Quick Reference for Important ParametersParameter Name Parameter Value Description 14presents important static system data parameters Parameter Name Parameter Values Description VSCBIPADDR1/2 VSCBPORTNUMBER1/2HSI Feature Configuration Parameter Name Parameter ValueAsymmetric Codec Treatment Empty Capability SetHairpin Configuring T.38 Fax on the Cisco Pstn Gateway Configuring T.38 Fax on a Cisco IOS H.323 GatewayConfiguring T.38 Fax on a Cisco IOS Mgcp Gateway 38 FaxConfiguring Clear Channel on the Cisco HSI HSI Support for Tech PrefixesClear Channel Parameters Example Value Example Configuration Configuring G.726 on the Cisco HSI Parameter Example Value Configuration Example Configuring the Payload Type for the MgcpConfiguring Cisco HSI g726-generic OL-4806-01 Rev. A14 Configuring G.729 Annex and G.729 Annex B ParameterOL-4806-01 Rev. A14
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H.323 specifications

Cisco Systems H.323 is a set of standards designed for transmitting audio, video, and data over packet-switched networks. It is a critical technology that enables real-time communication and has become integral to the world of VoIP (Voice over Internet Protocol) and video conferencing applications. Originally developed by the ITU-T, H.323 has been widely adopted and implemented by Cisco Systems, allowing organizations to leverage reliable and scalable communication solutions.

One of the standout features of H.323 is its ability to support interoperability among varying equipment and platforms. This means that devices from different manufacturers can communicate seamlessly, which is vital in a diverse technical environment. H.323 does this by defining protocols that handle signaling, media transport, and control, ensuring that various systems can work together effectively.

Key technologies utilized within H.323 include H.225 and H.245 signaling protocols. H.225 is responsible for call setup and management, establishing communication between endpoints. In contrast, H.245 manages the negotiation of media channels, allowing devices to configure themselves based on the capabilities of each other. This adaptability is crucial for dynamic network conditions typical in VoIP applications.

Another defining characteristic of H.323 is its support for multiple types of multimedia communication, including point-to-point and multipoint calls. This flexibility supports everything from simple audio calls to complex videoconferencing setups, where many participants can share video and audio streams concurrently. Cisco enhances this capability through its hardware and software offerings, optimizing performance for conference calls.

H.323 also features robust error resilience mechanisms. This ensures that real-time data, which is typically sensitive to delays and losses, can be transmitted with minimal disruption. Moreover, it facilitates quality of service (QoS) implementation, allowing organizations to prioritize voice and video traffic over less critical data services, thereby improving the overall user experience.

In conclusion, Cisco Systems H.323 stands out as a comprehensive solution for real-time communication over packet-based networks. Its main features, including interoperability, multimedia support, and enhanced error resilience, position it as a relevant technology in both corporate and personal communication settings. As organizations continue to adopt cloud and hybrid communication models, H.323 remains a reliable backbone for ensuring connectivity and collaboration across diverse platforms.
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