Need a SIP SDK for Visual Studio 2005

SIP is a complex protocol and, unless you have an overriding need to do so, I would not recommend trying to incorporate the handling of SIP directly within your application. It is likely to be much easier if your Visual Studio application communicates with an existing SIP product through an API. Take a look at Uniqall's Gridborg product. It can be installed on Windows or Linux and has a well documented API that your application links to through a socket. All the complexities of SIP are handled in the Gridborg application and you only need to tell it to answer a call, make a call, play a voice file, record a voice file etc. It is fairly reliable and the developers are accessible and responsive to any problems reported to them. Channel licenses are reasonably priced.
http://www.uniqall.com/home/introduction.php

Look, check out these Demos: http://www.vaxvoip.com/demo.asp  Then download one of the samples, and you will see that it isn't too complicated. Too expensive, yes. Complicated, no. I'm looking for a component/SDK that can achieve the same thing as the vaxvoip, but cost a fraction of the price. Thanks.

I assume it is expensive because it handles the complexity internally and took someone a long time to develop. I can't help you with SDK alternatives, but would recommend you look at Gridborg because it may meet all your requirements and its not so very different from an SDK if you run the Gridborg server on the same PC as your application. It just means there are two programs running instead of one.

Couple of alternatives for lower prices than VaxVoIP,

http://www.lanscapecorp.com/Store/index.asp

http://www.conaito.de/voip_standard_ueberblick.asp

There are quite a number out there with prices starting in the $300-400 range and up.  Though you will want to look closely at anything for your specific needs.  For example the $1500 package from VaxVoip handles 20 concurrent calls,  many of the lower priced packages are much more limited with 2, 4 or 6 calls.

Some of the softphones out there also provide SDKs to allow you to integrate with existing applications.  This is going to be limited in scope to the capabilities of the softphone it is based on.  
 
http://www.counterpath.com/index.php?menu=Products&smenu=sdk

There are also open source options though probably not as easy to use but very powerful,

http://www.sipfoundry.org/

Here's is a list of SIP various companies with SIP related development tools,

http://www.sipcenter.com/sip.nsf/html/Developers+Toolkit

As you can see many options.

Bottom line is cost to buy vs cost to implement and most of these packages will save a lot of time if they match your requirments well.  VoIP is also pretty hot topic so prices are going to remain high.  At least many of the choices are royalty free.

VAXVoIP has done well on the google rankings so thier name always comes out on top so you have to dig a bit to find other options.

My requirements are for 30 concurrent calls. So I guess VAXVoIP might be my best option after all is said and done, anyway? Moreover, even with the SIP softphone, the office will still require a VOIP PBX like asterix?

You dont necessarily need a PBX on site.  You can get virtual pbx setups through many voip providers where all you need are the soft or hard phones to connect.  Each is its own extension.  This does not allow for as much customization or control as has having your own PBX but it does work fine.

If you are looking for 30 concurrent calls I would think that you are heading toward some kind of pbx not jus a simple softphone.  You might want to look at whole pbx packages and not simply a SIP SDK.  Asterisk is a good base through there are also quite a few software packages out there for whole system development.

Do you actually need a softphone that can run 30 calls - or do you need a PBX that can handle 30 calls with X number of connected extensions?  If so each extension may only need 1 or 2 actual connections.  Many hardware business phones can only handle 4-6 actual lines max.

If you wish to outline what kind of application you are looking for we might be able to point you to something more specific.  Who knows there might be something that fits quite well that would allow you to avoid re-inventing the wheel - even if it does cost a few dollars.

 

Yes, I actually need a softphone, because I need to develop it into an application that people will be working with at the time that calls are being made, and calls must be recorded as well--well, at least some times, anyway. So yes, softphone definately, with my application logging time spend on calls, recording converstations, etc., all database integrated with the application.

couple more options to look at:
http://www.portsip.com/documentation.htm PortSIP
http://www.worksoutsoft.com/ inTEL(IP)hone SDK
the last link from Kode99 has a bunch of good options on it. Depending on what you're specifically, you're doing, I suggest you root around in there.

kode99, the application I'm developing requires that the user be able to make a phone call from within it, and log the number called as well as the lenght of time spent on the call, and sometimes even have the call recorded, co-relating all this information with other information from the application itself, into a database. So, I guess, like you said "You can get virtual pbx setups through many voip providers", I just need to integrate a softphone. That sound right to you?

Wow, kode99. You really know this stuff--I'm very impressed!--and immensely thankful and appreciative of the help and guidance you have so humbly provided me.  I'm convinced to go with vaxvoip.

It would be really cool if you had a website on your profile.

Many Thanks,

John
www.versacore.info

I'm not totally 'sold' on the price of VaxVoip myself.  Though if you use it for more than one project it will have pretty good value.  If you can use the demo to get your project up and running quickly you will at least get to see the value before commiting to it (or lack of value).

I do like that they offer multiple methods (ActiveX, dll, lib etc.) and support for several development platforms are also included.

Thanks for the feedback it is appreciated.  I keep a pretty low profile online,  probably should do a webpage sometime.