Telkom payphones connected using RAS card solution

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1 August 2001 Telecoms, Datacoms, Wireless, IoT

Telkom has installed a number of DIGI remote access server (RAS) cards to improve payphone service. The solution which was supplied by Tellumat, a channel partner of SPS South Africa, converts an analog payphone signal so that it can be switched digitally through Telkom's network direct to a front-end processor.

Tellumat has over 100 000 line-powered card payphones under licence from Anritsu of Japan installed at Telkom. According to Clive Pink, General Manager of Payphones at Tellumat, the solution was supplied after the previous analog system showed signs of reaching capacity.

"The traditional way of connecting payphones to the front-end server was via a modem, similar to the way we connect to the Internet," says Pink. "But a limiting factor of the payphone is that it is line-powered and operates on very low power, so the modem is a relatively slow V.23 modem. More recently, we introduced a V.22 modem into the field that improves data transfer speeds but still falls way short of the V.90 modems we use to connect PCs to the web."

After meeting with Telkom in 1997, Pink set out to find a cleaner, more integrated solution based on the ISDN Primary Rate Interface (PRI).

"Some time elapsed before I discovered the DIGI RAS30 and RAS4 cards," he says. "I had several failed attempts to convince ISDN card OEMs to change their software to accommodate the rather proprietary V.23 implementation in our payphone. All failed and then my search led me to DIGI via SPS. I was pleasantly surprised to have a visit from the DIGI development manager and sales manager - something was different: not only the determination of SPS management to help find a solution, but senior DIGI representatives as well!"

Pink says DIGI altered its firmware to accommodate the nonstandard version of V.23 used in the payphone.

"After some time we successfully integrated our payphones and front end server with the DIGI RAS30 card. It was a long road to my vision of a PRI interface for our FES, but in January 2000 it became a reality. DIGI has also recently completed an auto-recognition feature on the RAS30 cards to enable either a V.22 or V.23 payphone to call into the FES."

Pink says DIGI's readiness to address the SA market and solve the problem of the non-standard implementation of V.23 modem, and the personal involvement of SPS management, was the key to the solution. "Without their efforts we would not have it on the table today," he concludes.

For further information contact Martin Kuhlmann, SPS South Africa, (021) 794 3952, [email protected]

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Telkom payphones connected using RAS card solution

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