I'm getting ready to attend the International Telecoms Week (ITW) conference in Washington DC early next week.   ITW is targeted toward service providers, so it should offer a good chance to take the pulse of the VoIP industry in the aftermath of last year's reduced spending.   In the Dialogic booth (#720), we'll be talking about our IMG family of integrated media gateways and how they can be part of carrier solutions in areas like wholesale and retail Voice over IP, as well as SIP-based enhanced services. 

It may come as a surprise to many observers that there is still a substantial demand for connectivity between circuit networks controlled using Signaling System #7 (SS7) and the emerging world of Session Initiation Protocol (SIP) based networks and applications.   In fact, the demand for SS7 has not gone away at all, particularly given SS7's role as the most common signaling approach for voice networks in many countries and its role in supporting many popular services such as Roaming, Local Number Portability, Caller Name and Message Waiting Indication for voice mail.  

The SS7 call control approach is known as SS7 ISUP and is still the glue that ties together many voice networks for carriers of all different sizes, particularly the large incumbents.  Media gateways play an important role here, since many of the new core networks are based on the SIP, but subscribers are often still using the SS7 network.  There are multiple ways to connect between SS7 networks and the world of SIP, but the simplest approach is to use a media gateway which can support SS7 ISUP signaling on one side and SIP signaling on the other.  

I recently attended a carrier event where many application developers were present and it was striking how many of them have built their business around the idea of applications for phone networks that are purely based on SIP for signaling and RTP for media.  Since there are still a large number of subscribers that use a circuit based phone, media gateways offer the pathway that connects these users to the ever expanding realm of SIP-based applications.  

In addition to pure SS7 ISUP, there are also other ways in which SS7 shows up on carrier networks.   When a small carrier needs to order trunks these days, there are many options which include SIP, SIP-T, SIP-I and Sigtran M3UA.    Other than SIP, all of these options provide ways of preserving SS7 ISUP content, but transporting it over an IP network.  So there is a strong move toward using SIP for the core network and a variety of applications, but on the network edge, SS7 is still very common.  By using SIP-T, SIP-I or Sigtran M3UA, carriers can continue to utilize services built upon SS7, but are also able to take advantage of the superior economics offered by IP-based solutions.   When the protocols on both sides of a gateway are IP-based, the need for signaling translation or mediation still exists, but the concept of a media gateway then needs to morph into its all IP cousin, the multimedia border element.    

So SS7 is not going away in many carrier networks, but is showing up in these new and different forms.   As a result, I expect that carriers will continue to need ways to connect between the worlds of SS7 and SIP, and will often call upon media gateways and IP-based multimedia border elements as the preferred tools to accomplish that task.   If you're planning on attending the ITW conference next week and want to hear more about how to connect the worlds of SS7 and SIP, please stop by the Dialogic booth.