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REN constraint to 'phone line connections.

fotobits
Rising Star
Posts: 591
Fixes: 1
Registered: ‎23-06-2007

REN constraint to 'phone line connections.

Is the maximum of 4-RENs only applicable to the devices connected to the 'phone side of the Line Splitters, devices connected to the Broadband side, Modem/Digital Phones being disregarded?
Furthermore, am I correct in saying that cordless 'phones will only add to REN usage, the REN value of the Base Unit.
Regards......
5 REPLIES 5
BenTrimble
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 2,106
Registered: ‎06-02-2008

Re: REN constraint to 'phone line connections.

Hi, yes, all your assumptions are correct Smiley
fotobits
Rising Star
Posts: 591
Fixes: 1
Registered: ‎23-06-2007

Re: REN constraint to 'phone line connections.

Many thanks, Ben, for your prompt, concise reply.
Regards.....Noel
BenTrimble
Plusnet Alumni (retired)
Plusnet Alumni (retired)
Posts: 2,106
Registered: ‎06-02-2008

Re: REN constraint to 'phone line connections.

Haha, no worries! When I have more time to answer it includes extra info:
REN is an arbitrary number assigned to a specific electrical load - impedance - which is the resistance to AC. However, the assignment of this imedance includes a high DC resistance. A micro filter is a low pass filter (low frequency) pushed to the PSTN side and a high pass (high frequency) filter pushed to the ADSL side. An ADSL modem takes no power from the line and so has no REN rating.
Your cordless phone only loads the line at the base station, the handset itself and secondary handsets apply no direct load. These days modern phones load @ <1 REN so it rarely causes concern or problems, especially considering the prevalence of DECT multi-handset setups which are common where multiple phones are used.
Further reading:
http://en.wikipedia.org/wiki/Ringer_equivalence_number
http://en.wikipedia.org/wiki/Electrical_impedance
itsme
Grafter
Posts: 5,924
Thanks: 3
Registered: ‎07-04-2007

Re: REN constraint to 'phone line connections.

All the schematics I've seen for micro filters only have a low pass filter for the PSTN. It's a direct path from line to ADSL modem. No need to filter the ADSLside as the modem is a series of tuned circuits for each Bin.
fotobits
Rising Star
Posts: 591
Fixes: 1
Registered: ‎23-06-2007

Re: REN constraint to 'phone line connections.

Many thanks, Ben.
My 'phone Base Station is actually connected to the PSTN side via an Zyxel 'phone Adapter, which enables the selection, at the handset, of either a VoIP connection or a PSTN connection.  I assume that the Adapter's REN will be 1-REN...
Regards and thanks again, Ben....Noel