Cisco Systems ASR 1000 manual Information About Dtmf Interworking

C H A P T E R 3

DTMF Interworking

This chapter describes the importance and function of dual-tone multifrequency (DTMF) interworking between various signaling types and how DTMF is supported on the Integrated Session Border Controller.

For a complete description of commands used in this chapter, refer to the Cisco IOS Integrated Session Border Controller Command Reference.

Contents

•Information About DTMF Interworking, page 3-1

•RTP to SIP Interworking, page 3-2

•SIP to RTP Interworking, page 3-2

•Configuring Default Duration of a DTMF Event, page 3-2

Information About DTMF Interworking

One of the features of the Integrated Session Border Controller is the ability to interwork between the various dual-tone multifrequency (DTMF) signaling types. DTMF interworking is used when the two endpoints do not use the same type for relaying DTMF tones.

DTMF dialing consists of simultaneous voice-band tones generated when a button is pressed on a telephone. The challenge comes from a scenario where one side uses Real-time Transport Protocol (RTP) and the other uses Session Initiation Protocol (SIP) signaling to enable advanced telephony services. Examples of the types of services and platforms that are supported by DTMF interworking are various voice web browser services, Centrex switches or business service platforms, calling card services, and unified message servers. All of these applications require DTMF interworking for the user to communicate with the application outside of the media connection.

The Cisco ASR 1000 Series Aggregation Services Routers only support DTMF interworking between RTP and SIP DTMF indication types. This type of DTMF interworking provides for DTMF signals generated by SIP to be inserted into an RTP stream and RTP DTMF tones to be extracted and to generate a SIP message.

The following are ways of generating a DTMF tone:

•SIP digit detection and generation package—A SIP message is sent from the endpoint to the SIP proxy indicating that there has been a DTMF event, the type and the duration of the event.

Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers

OL-15421-01 3-1