CAS

Revision as of 10:38, 18 June 2010

Channel Associated Signaling is a signaling protocol for the set-up and tear-down of phone calls. It is different from other signaling protocols such as SS7 in that it is not message/packet-based but rather based on bit transition for state changing, and tone transmission for information and state information exchange. In many parts of the world, CAS was first replaced by ISDN and in many cases, was ultimately replaced by SS7. Today, CAS is often used with low density trunks.

CAS and TelcoBridges

CAS signaling is supported at the basic API level but is not supported at the Toolpack / Web Portal level and is thus not accessible for more basic applications (i.e., that don`t require programming code). TelcoBridges is scheduled to release support for CAS R2 within the Toolpack Web Portal v2.5 interface during the 3rd quarter of 2010.

CAS

Supported RBS T1 variants

The following CAS variants are currently supported at the basic API level:

• Wink start
• FXS Ground start
• FXS Loop start
• FXO
• Taiwan R1

Please contact TelcoBridges regarding support for additional CAS variants.

CAS R2

The TelcoBridges CAS R2 stack features a scriptable register signaling engine which practically allows the complete customization of communication process using tones. More specifically, it is possible to modify the timings of the tone exchanges, change the meanings of each tone and dynamically specify the sequence in which the tones are played. The stack also provides integrated interoperability between variants and between other signaling types. For instance, the call category can be converted between variants and propagated to a SS7 call leg.

Supported CAS R2 variants

• Generic (ITU spec base)
• Brazil

Using Toolpack, the variant scripts can be adapted them to fulfill different requirements and new scripts can be created from scratch.

References

Wikipedia article

ITU Q.400-Q.490 Specification