In article ,
wrote:

I used to see phones rated in terms of their "ringer equivalence" here in
the USA. These numbers were, for some phones, as low as 0.2. I do not
recall ever seeing one about 0.9. That would suggest to me that you could
readily have more than 4 phones on such a phone circuit. I never had any
reason to actually do a scientific test of this.

There is obviously a significant difference in the phone systems in the two
countries. Our phones have the bells in parallel and if thee are too many
the wrong impedance is presented to the exchange, and no ringing voltage
will get sent. I have never seen a UK approved phone with a REN less than
1, but there were plenty of 2s & 3s about at one time.

You can buy a REN booster ( a mains powered device) which allows many more
phones.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11