Phone makers mix memories

Electronic News, July 27, 1992 by Stuart Zipper

DENVER -- Telephone equipment manufacturers are experimenting with a mix of memory technologies--including ROM, pROM, EEpROM and flash memory--to store the roughly megabyte of code needed to support the next generation of ISDN telephones and terminal adapters.

The planned implementation of Integrated Services Digital Network-2 (ISDN-2) standards, and possible further generations of software, guarantees the ISDN-1 based customer premises equipment (CPE) now on the market will need up-to-date code to make use of new network features as they become available.

The result is that "Every one of us is building our equipment so we have rewritability," said David E. Morgan, Motorola's corporate director of computer and communications R&D. But, he cautioned, "Everybody's doing it differently."

In June, 1991, Bellcore published guidelines for CPE adhering to ISDN-1 specifications, and it plans to issue a similar volume for ISDN-2 by year-end. Telecom switch manufacturers, however, have not agreed to a common roll-out schedule for the features, putting CPE companies in the awkward position of second-guessing what equipment specs will be required.

"The manufacturers should make a business decision as to what is useful to sell terminal equipment," commented Al Vitenas, director of customer requirements at Bellcore.

Of the three main alternatives, most common in the market is EEpROM, which Motorola is using in its terminal adapters. Flash memory in CPE, a more expensive technology than standard EEpROM at least for now, is just starting to emerge from laboratories at such companies as Siemens Stromberg-Carlson, Northern Telecom and Motorola. All their systems use a desktop computer or other programming device into which the phone or adapter is plugged for reprogramming. An alternate system, championed by Fujitsu, is the use of non-programmable memory in cartridges which plug into the phone. Fujitsu started its program with pROM but has migrated to ROM, citing both circuit and programming costs.

The approaches being suggested by Bellcore call for downloading new code from the central office (CO) switch directly to the phone or terminal adapter, a position which is consistent with the CO-oriented strategy of Bellcore's Bell telephone company sponsors. That solution also would work with any of the available rewritable memory technologies. Vendors, however, are worrying it might be the most expensive solution as well.

Although the Bellcore spec has received some industry support, Eve Aretakis, director of switching product line management at Siemens-Stromberg, noted "The first issue is the cost of implementation from the switching side."

"If you're going to download, you have to have a system you're going to download from," added Robert Larribeau, director of marketing and product development for Fujitsu Network Switching of America. "Who's going to build that system, maintain it, provide all that support capability?"

Mr. Larribeau is chairman of the recently created CPE and Software Working Group of the ISDN User's Forum. He reported "a lot of concern at the meetings about supporting the cost of these things in (ISDN) terminals."

"You can't increase a telephone set by $100 or $200," agreed Ms. Aretakis. In contrast to the Fujitsu approach, though, the Siemens-Stromberg design requires a desktop computer to reprogram its model 787 ISDN phones, which use EEpROM.

David Thomson, general manager for residential and business terminals and services at Northern Telecom, figures the cost of the Bellcore system is too high. "An end buyer will compare that ISDN telephone to a digital Centrex."

Northern has likewise put its expectations on the use of a desktop computer to reprogram its EEpROM-based model 5317TDX ISDN phones. For some, the debate is irrelevant. Mr. Thomson argues that convertibility to the next ISDN standard is not important to customers who simply want bargain-basement ISDN service.

"If I choose to buy a cheap piece of CPE because I just make phone calls, why should I care about the capabilities of ISDN-2?," Mr. Thomson asked. Predicting ISDN proliferation will continue to be hobbled until ISDN phone sets decline in price, he added that today "75 percent of the telephones are sold for less than $75."

Mr. Thomson said Northern is also looking at nonprogrammable memories for low-priced ISDN offerings, with code in whatever technology costs least, probably masked ROM. Such phones, he conceded, would not be able to use new features as they come on line. But the phones would be compatible with new ISDN network software, so they would still work at the ISDN-1 level.

While Mr. Thomson sees the non-rewritable technology as the key to low-priced phones, Fujitsu sees ROM as the key to the least expensive upgrade technology possible. It has been offering cartridge software for more than two years on ISDN phones.

"Ours isn't as elegant as downloading, but it's very practical," argued Mr. Larribeau. "Basically you take a screw out and you take this little plastic cartridge out and replace it." Fujitsu's end-user retail price for the software cartridge in its phones currently lists at $80 to $90, a price expected to drop as volumes increase.