The 64 kbps leased line carries one 19,200 kbps RTU data stream and two E&M PAX telephone channels. Lines are leased over Türk Telekom’s Tellabs TDM network and a Tellabs STU-160 modem is installed at the customer side. At the TEİAŞ load dispatch centre the counterpart is a Tellabs Basic Node, connected via a single V.35 cable from the V.35 card on that node.
Why voice compression is mandatory
Multiplexer systems used on leased lines must be capable of voice compression (E&M, FXS, FXO), because carrying both PAX and RTU information over a 64 kbps line requires compression. A single voice channel is 64 kbps; as soon as it enters the multiplexer it is compressed to 8 kbps, and RS-232 ports carrying RTU information are added alongside it. Over its leased lines TEİAŞ requires at least 2 voice channels and 4 async RS-232 ports supporting 200–19,200 bps. The compressed voice and data are demultiplexed by the multiplexer at the far end, and voice/data transport operates correctly.
Products we deploy
For this solution our company installs Cisco 2800, 2900 and ISR series multiplexer-routers together with RAD Kilomux 2104 and Newbridge 3606 Mainstreet products. Cisco products are IP based, while RAD Kilomux 2104 and Newbridge 3606 Mainstreet are TDM based. The Cisco 2901 and 2911 are modular products designed to fit customer requirements; being modular, any interface added later can be supported with additional cards without replacing the unit.
| Product | Architecture | Note |
|---|---|---|
| Cisco 2800 / 2900 / ISR series | IP based | Modular card design, interfaces can be added later |
| RAD Kilomux 2104 | TDM based | Multiplexer with voice compression |
| Newbridge 3606 Mainstreet | TDM based | Classic TDM multiplexer |
| Tellabs STU-160 | Modem | Customer-side termination |