Connecting to an ASR (Automatic Speech Recognition) Server

Introduction

You connect to an Automatic Speech Recognition server over RTP using the Record File Start 0x011E message. If you are also using Positive Voice Detection, you would use the Record File Modify 0x011F message.

Basic Implementation

You would use the Record File Start 0x011E message with the following TLVs:

Mandatory TLVs

0x0687 - Enable RTP for Play/Record File (0x01 - Enable)

0x29FF Media Local End Point Information

0x2A00 Media Remote End Point Information

Nested TLVs (used with 0x29FF and 0x2A00)

0x2A01 Media Per Stream Information

0x2A07 Media Port

0x2A0E Media Connection Address

See About Nested TLVs for Media Streaming

Optional TLVs

0x0688 - RTP Record Mode (to use RTP with Positive Voice Detection)

Example Call Trace

00 78 01 1e 00 00 ff 00 02 0d 03 00 00 00 01 01 04

00 0b 'Number of TLVs

05 e0 00 04 00 00 00 0a 'File ID Tag

05 e1 00 02 00 01 'File Format

05 e3 00 01 03 'Optional Gain Tag

05 e6 00 01 0c 'Optional File Event Descriptor

05 e8 00 05 00 03 e8 c8 fd 'Optional Beep Tone Parameters

05 e9 00 02 ff ff 'Disable Initial Silence Timer

05 ea 00 02 ff ff 'Optional Final Silence Timer

06 87 00 01 01 'Enable RTP

06 88 00 01 00 'Optional Record Mode Continous Recording

29 ff 00 14 'Local End Media Info

2a 0e 00 04 87 77 2c 3c 'Local Media Connection Address

2a 01 00 08 'Per Media Stream Information

2a 07 00 04 00 00 17 70 'Local Media Port

2a 00 00 14 'Remote End Media Info

2a 0e 00 04 87 77 2c 32 'Remote Media Connection Address

2a 01 00 08 'Per Media Stream Information

2a 07 00 04 00 00 17 72 'Remote Media Port