Archive for the 'SIP' Category

The Eagle Has Landed…and so has Kapanga for Android

Monday, July 20th, 2009 by Martin Cadirola

Today is a very special day for all of us here at Kapanga.

40 years ago, one of the major events of modern era took place -landing humans on the Moon and returning them safely back home.

We thought of letting you about our recent development deserving news -kind of our own little achievement.

We have now a Kapanga Voice client running on our beloved G1 Google Phone, using the Android operating system. This time the release will be by invite-only so we’ll have a form for you to sign up very soon.

In a way, we are also thankful to NASA’s Apollo program since we wouldn’t have gone into engineering and science have we not had such an example of teamwork applied to achieving a near impossible goal. Indeed we are huge NASA fans!

All the best and thanks for the continued support!

Skype down…SIP up?

Thursday, August 16th, 2007 by Martin Cadirola

This morning I learned that Skype has been down due to a “software failure” leaving millions of people unable to use it. I know lots of people use Skype for their personal and business use. I won’t be celebrating this problem even though they are an indirect competitor. What I’m interested in pointing here is that telecom carriers, operators, and service providers will use this glitch to their advantage. My question is how can we ensure that a SIP-based infrastructure can be more reliable than a peer-to-peer framework? All we know is that SIP is here to stay and service providers should be able to ensure reliability from working with far less subscribers than Skype.

For those that want to read more about the Skype glitch, you can read here and here. Oh, and here is an update.

Introducing Kapanga Mobile Edition (Beta)!

Wednesday, December 13th, 2006 by Martin Cadirola

You may have noticed a few posts in our blog…and here’s the reason why: working very hard to release a public beta of Kapanga Softphone - Mobile Edition :>D . Kapanga Mobile has been in development for over a year and the good news is that it’s been tested with quite a number of large companies. All of us here at the Kapanga Team are strong believers in public feedback and already appreciate the kind words of encouragement. For those who have not seen the press release, click here; you can try the beta by completing the form here. Cheers!

How does an Internet Telephony Provider works?

Thursday, November 2nd, 2006 by Martin Cadirola

Since we are mostly interested about what happens on the endpoint side of the VoIP picture, we thought it would be interesting to summarize the components of an Internet Telephony Service Provider (ITSP). So here is a brief of list of main components:

- User Agent Client (a.k.a SIP client)
- Registrar Server (provides network access)
- SIP Proxy Server (routes calls)
- User Agent Media Gateway (converts VoIP calls to PSTN calls)
- PSTN access (T1 line connected to a CO (Phone Central Office)
- PSTN telephone (the good ol’ telephone)

When we start Kapanga (or any other UAC), it registers with the Registrar Server to gain access to the network. Thus, Kapanga will send a “SIP REGISTER” request with its credentials and the Registrar Server will validate and grant it access to the network. Once we place a call to a regular number (a.k.a. PSTN number in tech jargon) the call will traverse the network and eventually will get routed to a User Agent Media Gateway at the ITSP site.

The Media Gateway will take care of translating SIP calls to ISDN or SS7 format (and viceversa), routing calls back to the SIP Proxy Server as needed. The SIP Proxy Server will check its routing list to make sure the destination device is available (in this case Kapanga) and whether to forward the call to a Voice Mail system or to Kapanga itself. The media content (voice or video) will then traverse the IP network from the Gateway to Kapanga (the User Agent Client) directly without going through any SIP Proxy Server.

And voilá! That’s how it all works. Of course, if you are offering this as a service, you’ll want to add a billing server that keeps tracks of calls/minutes/rates. We’ll get to that in upcoming posts. Cheers!

Fax over IP: How does it really work?

Friday, September 22nd, 2006 by Martin Cadirola

Fax over IP is one of the great features of Kapanga Softphone. From time to time, our prospects asks us about what actual benefit our implementation of Fax over IP brings to the table. Our answer is simple: reliability.

There are two ways of sending faxes over IP; one is transporting the fax tones over RTP (Real-Time Transport Protocol) just like plugging your standard fax machine to the ATA device from your provider; the other is transporting the binary information the fax tones carry using IFP (Internet Fax Protocol). The latter method is standardized by the International Telecommunications Union (ITU) under the T.38 specification. We at Kapanga Softphone implemented T.38 support and built it into the softphone.

Why is then T.38 the recommended way to send faxes over IP? Here are a few key reasons:

1. Transporting fax tones (and tones in general) over RTP is unreliable when using voice low bit rate codecs. In other words, sending a fax using G.723 is virtually impossible due to the distortion introduced by the transcoding.

2. When a fax is traveling through RTP, even the slightest presence of echo prevents the end points from demodulating (=receiving) fax tones correctly.

3. T.38 is the preferred option for end points like softphones and media servers since generating and receiving fax tone signals in audio requires a lot of CPU power.

4. T.38 provides embedded redundancy and error correction methods, resulting in a more reliable way of transmitting fax over IP than RTP.

Thus fax sent using T.38 through an IP network will result in a very reliable solution for both sending and receiving fax .