Wireless VoIP Demystified

Martin Sauter has a three part post with some great technical information about VoIP, specifically he talks about UMA, SIP, and IMS.

From the UMA post:

“First on the list is UMA, a 3GPP standard like GSM and UMTS, loved and feared alike by mobile operators (or carriers as you say in the U.S.). The principle of UMA is simple: It replaces the GSM radio technology on the lower protocol layers of the mobile phone with Wireless LAN. A call is then tunneled via a Wifi Access Point connected to a DSL/cable modem via the Internet and a gateway to the Mobile Switching Center (MSC) of a mobile network operator. The gateway between the Internet and the network of the mobile operator is called a UMA Network Controller and one of the companies developing such a network node is Kineto Wireless.”

From the SIP post:

“The basic architecture of SIP is simple: A SIP server in the network forms the central element of a VoIP network. VoIP clients are either software clients on PCs or notebooks or standalone devices like phones with an Ethernet port. When connected to an IP network their first task is to register their IP address with the SIP server. To call another device, a SIP client then sends a request to the SIP server. The SIP server then retrieves the IP address of the destination device from its database and contacts the destination device. If the destination device is willing to accept the call, the server informs the originator of the IP address of the destination device and a direct IP connection is established between the two parties.”

From the IMS post:

“IMS standardizes a service framework and a protocol between the IMS core and application servers that allows third parties to create new services based on IMS and SIP commands. Such services are for example instant messaging, presence, voice mail, video mail, location based services, short dialing numbers, private dialing plans, music and video streaming, push to talk, etc.”


About Daniel Davenport

Daniel is a digital media executive with internet and broadcast experience. Daniel is currently the executive strategy director at THINK Interactive.

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