31-03-2010, 03:02 PM
VoDSL
The VoDSL (Voice over DSL) decodes signaling messages that are exchanged over VoDSL network and protocols used over LES ATM-AAL2 links. The main purpose of the signaling messages are to allocate AAL2 channels, activate user IAD ports, manage the customer premises IAD through the EOC management channel and to set and release POTS and ISDN calls. The whole concept of VoDSL is to support multiple voice calls, either inbound or outbound, over a single DSL circuit, while simultaneously supporting high speed Internet access. VoDSL is based on a number of standards. this non standard technology which is based on a number of standards does transmissions in digital format, unlike the hybrid analog/digital approach found in ADSL and ADSL Lite.
SDSL (Symmetric DSL) and S-HDSL (Single-pair High-data-rate DSL) are the few of the several DSL options over which VoDSL runs. The former is a perfectly symmetrical version, with equal amounts of bandwidth both downstream and upstream and runs at signaling rates as high as 1.544 Mbps, which is equivalent to T1 speed, over distances up to 2 miles or so. SDSL also can be adjusted downward to run at rates of 384 Kbps and 128 Kbps. The latter is standardized as G.991.2, runs at rates up to 2.3 Mbps over distances well beyond the typical DSL limit of 18,000 feet, and it does so over a single UTP copper pair.
