Activate Email 
INDUSTRIES
INDUSTRIES
SIP and Open Standards Featured Article
October 30, 2007
Zhink Releases Skype-to-VoIP Gateway
By Tom Keating, Chief Technology Officer and Executive Editor
You recall my story about the SIP
to Skype (News - Alert) gateway breaking Skype's “Great Wall of VoIP,” right? You don't? Well, let me refresh your memory. I wrote:
to Skype (News - Alert) gateway breaking Skype's “Great Wall of VoIP,” right? You don't? Well, let me refresh your memory. I wrote:As most techies know, Skype uses a proprietary protocol and does not support inbound SIP calls. If you ask Skype CEO, Niklas Zennstrom why Skype chose its own proprietary protocol, (which many reporters have asked him), he always gives the same canned reply: that the company chose its own proprietary protocol because SIP doesn't do everything they need, SIP has issues traversing firewalls, the company’s proprietary protocol is more flexible, blah blah blah. Even though there are now NAT traversal solutions for SIP that perhaps didn't exist a couple of years ago, Skype still hasn't moved to SIP and it doesn't look like it will.
traversal solutions for SIP that perhaps didn't exist a couple of years ago, Skype still hasn't moved to SIP and it doesn't look like it will.Part of my post above ranted regarding the fact that SIP-based softphone users can't communicate with Skype users. Well, today I learned that a new Skype-to-SIP gateway called Skype SIP Gateway (News - Alert) (PE) 1.0 from Zhink.com was recently released. This product allows two callers, one on Skype and the other with a SIP address, to communicate with each other. Sweet! By configuring this product and any SIP server (such as OpenSER, Asterisk (News - Alert), etc.) correctly, you can come up with many interesting working scenarios.
The following possible scenarios are listed on the Zhink.com Web site:
- Forward Skype callers who are your friends to your mobile number. This is very much like personal “skypeout.”
- Reject all Skype callers whom you do not know.
- Allow yourself and family members with own Skype accounts to call into interactive voice response system provided by SIP server. With this, you can do things like access your voice mails or dial out to PSTN lines.
- Using multiple Skype To Sip Gateways, you can now allow SIP users on different private SIP servers to communicate, using the gateways to provide internet connection via Skype network. This is much like local PBXs of branches of a company connected via Internet. Note: This will require multiple PCs, each hosting one Personal Edition of this gateway.
- Allow SIP users on softphones like Ekiga, X-Lite and many others to contact Skype callers directly. The Sip users need not have Skype accounts.
Here are some screenshots of the software:
This last screenshot is interesting because I noticed it is using the jackd daemon. The jackd daemon is part of JACK, "a low-latency audio server, written for POSIX conformant operating systems such as GNU/Linux and Apple's (News - Alert) OS X. It can connect a number of different applications to an audio device, as well as allowing them to share audio between themselves. Its clients can run in their own processes (i.e. as normal applications), or can they can run within the JACK server."
Obviously, JACK must be that heart of how this application works. It must be “muxing” the audio from the Skype application into a standard SIP call using the RTP stream. Ironic, that since this requires JACK, this Skype to SIP gateway only runs on Linux—which is often the last operating system to get Skype updates. The software allows you to talk for 1 minute for free without registration. It costs $25 to register. Sounds like a cool application to try out.
Obviously, JACK must be that heart of how this application works. It must be “muxing” the audio from the Skype application into a standard SIP call using the RTP
stream. Ironic, that since this requires JACK, this Skype to SIP gateway only runs on Linux—which is often the last operating system to get Skype updates. The software allows you to talk for 1 minute for free without registration. It costs $25 to register. Sounds like a cool application to try out. Want to learn more about the topic covered in this article? Check out TMCnet’s White Paper Library, a collection of in-depth information on relevant topics affecting the IP communications industry. This information is free to registered users.
Tom Keating is Vice President and Chief Technology Officer at Technology Marketing Corporation, and Executive Technology Editor/SEO Director for TMCnet.com. He also blogs for TMCnet here.
