CRBT is written as Color Ring Back Tone, Caller Ring Back Tone, or Personal Ring Back Tone (PRBT), is a latest services that can be utilized by telephone user where he can select music or audio clip, including ring back tone standard, until the call is connected. For mobile user, people that want to be connected by the caller are able to set ringback tone as their desire so the caller can listen to the music until the calling is connected.

When we want to call someone, we used to be waiting telephone call with hearing a common tone (tut-tut-tut), which is boring and monotonous. With color ring back tone, user can listen his favorite music, jingle or even a uniqe sentences that can be heared by the caller. This new feature presents a unique service. This service may relieve stress/bored for telephone user, because if we wait for the call with standard boring ringtone, especially when the call cannot be connected (not hang up).

Today’s cellular users in Indonesia have started to use this service. TELKOMSEL, Cellular operator that has the biggest subscriber at this time, has launched this service since September 1, 2004, for user of HALO, Simpati, and AS Card in Jabotabek area, then followed by other areas in all Indonesia. To launch this latest product, Telkomsel cooperates with Sony Music Indonesia and SK Telecom Consortium. SK Telecom as integrator system is the creator of this service and first operator in the world that launches this kind of service.

Implementation of CRBT and SS7

The core of CRBT service is a PSTN server that is connected to MSCs (Mobile Switching Centers) carry out data like CRBT clip. Topology of CRBT can be seen in figure below:

Figure 1. Implementation of using SS7

Functions of music/voice ring back tone Server are:

  1. Dial up music/clip voice until telephone connects
  2. Act as SSP proxy, which has function to end up SS7 as a sign that telephone is successfully connecting.
  3. Accumulate music/clip voice that is mostly used
  4. Host of Main Application as SSP to communicate with SS7 SCP.

Content Provider could be like ISP database, or operator himself. Database contents various clips offered to subscribers. User can access Content Provider anytime, they can choose a clip, change it or make new clip by combining them with or without personal message. There are three ways for subscriber to access database content provider, they are:

  • Via WEB (by choosing a clip of available list, each clip has its clip ID number)
  • Send SMS to operator server
  • Accessing IVR operator (via fixed or mobile telephone call)

Call Flow to establish the call with CRBT

Figure 2. Call Flow for Call Establishment CRB

CALL FLOW ESTABLISHMENT

Figure 3. Call Establishment CRBT

Conclusion

See the offering feature and the advantage in subscriber or company side, the service of Color Ring Back Tone is very promising. This is absolutely become cellular operator’s notice. They compete to develop the service and give the best service as they can. For people whom they think cellular telephone is as important as money, this service is the most favorite thing. The service makes a huge change in mobile phone world. Compared to the existing service such as downloading ringtone, CRBT has its own superiority for service provider, like it can attract new subscriber and still keep old user. Unsurprised if cellular observer conclude that it is a service that they have been waiting for taking profit greatly.

Reference

http://h20208.www2.hp.com/opencall/library/products/media/ocmp/ColoRing_RingBack_SB.pdf

http://resource.intel.com/telecom/support/appnotes/8933/8933an.pdf

http://www.komputeraktif.com

Andreas W. Yanuardi, author is engineer in Technology Information and Solution laboratory, TELKOMRisTI.