H.248

Also known as Megaco, H.248 is a protocol for controlling media gateways via a softswitch or a Media Gateway Controller (MGC).

TelcoBridges and H.248

Toolpack now supports the H.248 protocol.

As indicated in the diagram below, the H.248 stack is a module in the media gateway application residing on the application server. It communicates with the various Toolpack classes (CAFClass, CMC Library, CMC Class) as required via a new Media Leg API. In turn, the media gateway application communicates with the softswitch / media gateway controller via the H.248 protocol.

H.248 package support

Toolpack supports the following packages.

• H.248.1
  • Protocol v2
  • IPSec connection support
  • Support UDP (2944 or user-defined)

• H.248.1 - Basic packages
  • Generic
  • Base Root
  • Tone generator (for extension purposes only)
  • Tone detection (for extension purposes only)
  • Basic DTMF generation
  • DTMF detection
  • Call Progress Tones Generator (Ringing, Busy, Congestion and Warning tones supported)
  • Basic continuity package
  • Network package
  • RTP package
  • TDM Circuit package (only echo-cancellation)

• H.248.2 Facsimile, text conversation and call discrimination packages
  • Fax/TextPhone/Modem tones detection (fax and data only)
  • Call type discrimination package (fax and data only)
  • IP Fax (Event: Fax Connection Change - end of fax session, call terminating)

• H.248.4 Transport over Stream Control Transmission Protocol (SCTP)
  • Partial support

• H.248.7 Generic announcement package
  • Generic announcement package (Fix Announcement play only)

• H.248.10 Media gateway resource congestion handling package
  • Congestion handling package

• H.248.11 Media gateway overload control package
  • Overload control package

• H.248.13 Quality alert ceasing package
  • Quality alert ceasing package

• H.248.14 Inactivity timer package
  • Inactivity timer package

• H.248.16 Enhanced digit collection packages and procedures
  • Extended DTMF detection package
  • Enhanced DTMF detection package

• H.248.23 Enhanced alerting packages
  • Enhanced alerting package

• H.248.25 Basic CAS packages
  • Basic CAS package
  • Basic CAS addressing

• H.248.27 Supplemental tones packages
  • Carrier tones generation package
  • Diagnostic tones generation package

• H.248.28 International CAS packages
  • International CAS
  • CAS blocking

• H.248.29 International CAS compelled register signaling packages
  • Annex A.1 only in 'enbloc' compelled mode (International CAS Compelled package - No digitmap control: Digitmaps are preconfigured on MG)

• Q.1950 packages
  • Basic call progress tones generator package
  • Expanded call progress tones generator package
  • Basic services tones generator package

Additional details

• Support for text mode only

Configuration

• Web Portal v2.8: H.248 Configuration
• Web Portal v2.7: H.248 Configuration
• Configuring H.248 on TMG devices (v2.6 and before)

References

• Wikipedia article