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  1. Signaling System No. 7-Based Services
  2. Signaling System No. 7: The Key to Convergence
  3. Summary
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Signaling System No. 7: The Key to Convergence

Telecommunications network operators can realize increased investment returns by marrying existing SS7/C7 and intelligent networking infrastructures with Internet and other data-centric technologies. SS7/C7 is a key protocol for bridging the telecom and datacom worlds.

The following sections describe the exemplar hybrid network services that SS7/C7 enable:

  • Internet Call Waiting

  • Internet Calling Name Services

  • Click-to-Dial Applications

  • Web-Browser-Based Telecommunication Services

  • WLAN "Hotspot" Billing

  • Location-Based Games

Internet Call Waiting and Internet Calling Name Services

Internet call waiting is a software solution that alerts online Internet users with a call-waiting message on their computer screens when a telephone call enters the same phone line they use for their Internet service. The user can then send the call to voice mail, accept the call, or reject it.

Some providers linking it to CNAM, as mentioned in Calling Name (CNAM), have enhanced the Internet call-waiting service. This service is known as Internet calling name service, and it provides the calling party's name and number.

Click-to-Dial Applications

Click-to-dial applications are another SS7-IP growth area. An example of a click-to-dial application is the ability to click a person's telephone number in an email signature to place a call. These types of services are particularly beneficial to subscribers because they do not require them to change their equipment or access technologies; a POTS and a traditional handset are the only requirements.

Web-Browser-Based of Telecommunication Services

Over the coming decade, we are likely to witness an increase in web based telecommunications services. An example is customer self-provisioning via the Internet, a practice that has been in the marketplace for some time and is likely to increase in both complexity and usage. A customer can already assign himself a premium or toll-free "number for life" via the Internet. The customer can subsequently use a Web interface to change the destination number it points to at will, so that during the day it points to the customer's office phone, and in the evening it points to the customer's cell phone, and so forth.

Another example is the "call me" service, which allows a customer to navigate a Web page to arrange a callback from a department, rather than navigating interactive voice response (IVR) systems through the use of voice prompts and a touch-tone phone.

The potential extends far beyond traditional telecommunications services, to the point where the distinction between Web and telecommunications services is blurred. An example of such an enabling technology is Voice Extensible Markup Language (VoiceXML), which extends Web applications to telephones and shields application authors from low-level, platform-specific interactive voice response (IVR) and call control details.

The marriage is not only between SS7/C7, the Internet, and fixed-line networks—it also extends to cellular networks. Plans are underway to put the location-based information and signaling found in cellular networks into hybrid use. For example, Web-based messenger services could access cellular network home location registers (HLRs) to enable a user to locate a friend or relative in terms of real-time geographic location.

WLAN "Hotspot" Billing

SS7/C7 has recently begun playing a role in the marriage of wireless (WLANs) and cellular networks. A subscriber can use a cellular subscriber identity module (SIM) card for authentication and billing purposes from a WLAN hotspot. For example, if a subscriber is at a caf  with WLAN facilities (typically wi-fi), the subscriber can request permission to use the service via a laptop screen. This request triggers a short cellular call to authenticate the subscriber (using SS7/C7 signaling). The usage is then conveniently billed to the subscriber's cellular phone bill.


A SIM is used in 2nd generation cellular networks based on GSM, and on 2.5/3G networks as defined by 3GPP. A SIM contains the subscriber's identity so that the subscriber can change cellular equipment freely by simply changing the SIM card over to the new device. This means that the subscriber can plug the SIM into a new cellular handset and the number "transfers" to that handset, along with the billing.

Location-Based Games

SS7/C7 is not only used to deliver games to cell phones, but it also plays a role in the creation of a new genre of location-based games and entertainment. Cellular games incorporate the player's location using SS7/C7 to provide mobility information a dedicated web site as a central point. Some of the games that are emerging at the time of this writing are using global positioning system (GPS), WLAN support, and built-in instant messaging capabilities (to help tease your opponents) to blend higher location accuracy.

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