1989 Norstar Meridian Field Trial NT8B50 (M7900)
This field trial development set, initially designated as a “NT8B50,”
evolved into the Norstar Meridian M7900 Touchphone.
Meridian M7900 Northern Telecom’s second prototype Touchphone after the M3000.
A telephone with all indicators and functions managed by a Touchscreen.

As received January 18th 2024.

This Touchphone is labelled with a BT logo. A former employee commented: I was on the day 1 Norstar team; mid-80s. If my memory is close; I’d place M7900 delivery around 1988. BT was Norstar’s first and largest European distribution / telco customer. They shared the Phone Applications market vision M7900 was attempting to enable. So they were distributors for all Norstar products and put their own brand on them (like most phone companies). They had their brand on a bunch of other Nortel products as well.

Added a KSU Norstar 616 non DS and running DR5 software, plus a ATA NT8B90CA.

The screen saver automatically powers down after a period of inactivity.

Meridian M7900 Northern Telecom’s second prototype Touchphone after the M3000.

A quote from former BNR empolyee on the M3000.
I worked at Nortel in the 80s – in the Design Interpretive group under John Tyson.
“My contribution was on the product definition and user interface design side. As far as I know, when we were working on it, it was the first phone to use a touch-sensitive screen.”

https://www.oldtelephoneroom.ca/norstar-meridian-sl-100-m3000-touchphone/