R4+Z

It comes down to whether the analogue interface for the Asterisk supports message wait! I hate to have to say this (I don't really). This is what you get for expecting computer experts to know telephone systems. Might I suggest you ask in the Asterisk forum (assuming there is one!)

mcmas

R4+Z, you are so right!
I got my first inkling that the (young) tech doing our configuration was not a phoneguy's bootlace when I emailed him asking that the RNA timeout be extended to 30 seconds, and he emailed back: "What's RNA?"

Hence my participation here. I figure if I can find out what Asterisk needs to do, then tell the tech, he may be able to find a way of getting asterisk to do it.

To be fair to the nerds, they deal mainly with IP phones, which handle message waiting lights etc. very nicely. But I can't afford to replace all of our 50 or so analogue phones just yet.

HELP! Can someone tell me what a NEAX 2400 SDS/VS (or pretty well any PABX) sends to an analogue phone to turn on its message lights?

mcmas

R4+Z

Basically the voltage is increased to 80V

mcmas

R4+Z, right again.
I talked to an old NEC tech, and he stressed that it is 80volts AC that is put on the line.
Thanks.
mcmas

paulzhen

NEC PBX put +80V DC on th analogue line, Digital or IP-Phone turn on MW by NEC protmis protocol.
Nortel put +100V DC on the analogue line.

mcmas

Thanks. But I did hear from a very experienced old NEC technician, who agreed with your statement of 80V, but insisted that it ought to be AC, not DC.

smoom

The Grandstream GXW4008 ATA does not support analog message waiting.

mcmas

You're darn right the Grandstream GXW4008 doesn't support lighting message lights on analog extensions.
Where would it get 80v from?

When I started this thread, I didn't know how analogue extension message lights were turned on, and wondered if there was some kind of kludge or workaround. Once I found it required the application of a steady 80v across the analog pair, I gave the idea up.

I wonder what voltage is required to ring an analog extension?
I imagine it would be some tens of volts.
And where does a GXW source that voltage from?
Just passes it through from an Asterisk box?
But they run on low-voltage DC also.
?
mcmas

smoom

In the US a typical analog line from the phone company would be -45vdc to -53vdc(usually 48vdc), a line from a PBX or the Grandstream would be 21vdc to 27.5vdc (usually 24vdc)....(and before any one post to tell me I'm wrong there there are different line cards in phone system's that supply more or less voltage) Ring voltage would be 90VAC at 20 cycles per second, with a true sine wave. A message waiting light like the 2400 used was 90 to 140VDC (usually 90vdc) on the line when the phone is on hook. Since the message waiting light uses DC voltage it will not cause the phone to ring, but it may ding once as the voltage is applied. A majority of phone companies in the US use Studder DIal tone to signal a user that they have voicemail. Studder dial tone is where the dial tone you hear instead of being a solid tone is broken. Studder dial is slowly starting to fade away, because for users to know if they have a message they have to lift the handset on there phone. With only a few users it is not a problem but with thousands of users checking for voicemail it causes the phone company's switch to slow dial and require more register sender cards (cards that supply dial tone). The grandstream like most newer devices coming on the market today use FSK signalling for caller ID and message waiting. FSK signalling is a lot like caller ID on your home phone where the phone company sends a momentary data burst down the line while the phone is on the hook. This data burst will tell the phone to turn on a message waiting light.

I found this on Grandstream'ss website.
Message indicator is a special on-hook caller ID type message that enables and disables the message waiting light on certain phones. GXW4008 has this feature enabled by default. However, certain phones (rare) that do not support it may mistakenly treat this CID signal as an incoming call. A configuration option is needed to turn on MWI in this case.

So I was wrong to a point the Grandstream does not support the Message waiting lights on your current phones but you could replace the phones with newer sets that support FSK and it would work.

The voltage the Grandstream uses to ring the phones and give dial tone comes from the power cube supplied with the unit. The Grandstream only supports 1 device per port so it does not need a large power supply like the phone system uses.

Hope this helps