TOPIC: Softswitches and media gateways in Voip

i m pretty much interested in Voip network if someone cud explain how voip actually works , i m into asterisk so i know the basic stuff but not how it actually packetized the voice on to ip packet.
Moreover i would like to know how Media gateways and Softswitches work in this perspective.
oh and i just wana know if we can upload any files (like network diag) in the forum msg?possible?
anyone?

Rgds

Taqqi

hi..
About voip you can get useful information here
electronics.howstuffworks.com/ip-telephony.htm

Media Gateway : The MGW handles the media, or bearer, interface. It converts media from the format used in one network to the format required in another network. For example, it can terminate the TDM trunks from the PSTN, packetize and optionally compress the audio signals, and then deliver the packets to the IP network using the Real Time Protocol (RTP)

Softswitch: is a general purpose computer running specialized software that turns it into a smart phone switch. Softswitches cost significantly less that tradition circuit switches and can provide more functionality in particular, in addition to handling the traditional circuit switching functions, Softswitch can convert a stream of digitized voice bits into packets, this opens up a number of options for transmission, including voip approach.

In any telephone network, the most complex element is the software that controls call processing. This software performs call routing and implements call-processing logic for hundreds of custom calling features. This software runs on a proprietary processor that integrated with the physical circuit-switching hardware, a more flexible approach is to physically separate the call processing function from the hardware switching function. In Softswitch terminology, the physical switching function is performed by media gateway and the call processing logic resides is a media gateway controller.

Note: my answer is depended on the documents that I have in my job in a 3G operator when we use Softswitch terminology. I have no idea about using Softswitch in Data Networks.

I build CLEC service provider VOIP network and your questions are toooooooo broad. You want to know what media gateways do? Which media gateways? Lines or trunks? Voice packetizaton is done on the DSPs based on the codecs used. It converts analog voice to digital voice in terms of sampling. As part of that conversion it also creates the UDP/RTP packets to send out the network side interface. Trunk media gateways have TDM interfaces on one side and IP interfaces on the other side. Lines gateways are CPE devices that has analog output on one side and network interface on the other side.

Trunk gateways have TDM trunks to other CLECS in the same rate center, you can drop this traffic off at the end office or at the tandem depending on the amount of traffic. Most providers will allow you to drop off your traffic to their customers at the tandem until you reached a certain level of traffic then you are required to drop your traffic off at the end office servicing the particular rate center. The trunk gateways are your link to the rest of the PSTN. Routing traffic to these gateways are based on translations per rate center in the softswitch. At a minimium you need LD trunks, Local trunks, and 911 trunks; but it's much much much more complex than that on CLEC level. If this doesn't make any sense, perhaps you need to re-ask your question in a different manner or as narrower questions.