HealthNut's profile

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Thursday, January 12th, 2023 10:52 PM

AT&T 1820 answering machine not working with VOIP adapter

I have an old AT&T 1820 telephone / answering machine (circa 1995) which works well on my landline and reliably answers after 4 rings.

I recently switched to VoIP service, with a Grandstream HT802 adapter. The telephone works with the adapter, but the answering machine is somehow not detecting the ring cycles properly and never picks up.

The "cadence" for the primary ringtone sent by the adapter is set to 2000/4000 (2 sec on, 4 sec off) which is the US standard. I tried tweaking that slightly up/down with no effect.  Are there any other parameters that might affect the answering function?

spoom2

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18K Messages

5 months ago

Ringing voltage is around 90 volts at 20hz so you really can't measure it, unless you have a meter that reads 20hz. Your phone's tone ringer is pretty tolerant of the voltage and frequency, your old answering machine probably isn't. I don't think the ATA is putting out the correct voltage or frequency. If you have a phone with a bell ringer see if it will ring it. I'm betting it won't. The FCC says the REN (ringer equivalent number) is supposed to be 5 REN it's probably not even close. As a comparison a tone ringer in newer phones has a half REN at the most  

(edited)

spoom2

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18K Messages

5 months ago

Well in reading through the specs it says the 801 has a 5 REN output, but the 802 only has 2 REN, which still should be enough a REN means it will ring 1 old fashion 500 type telephone, so 2 Ren would ring two. Have you tried it with just the answering machine hooked up with nothing else? I don't see anything in the specs that addresses ringing voltage or frequency. 

(edited)

spoom2

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18K Messages

5 months ago

According to Grandstreams forum the unit isn't capable of putting out anywhere near 90 volts.  Sounds like you're going to need a ring booster to boost the ringing output of the VoIP ATA

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2 Messages

5 months ago

Thanks for the research and the quick reply!  The AT&T 1820 is a combo phone / answering machine and is labelled: "Ringer Equivalence: 0.4A  0.7B". It's the only device connected to the adapter. The ringer frequency on the adapter was set to 20 Hz, and it has a "high ring power" option, but that didn't work either. 

I found this comment elsewhere: "Analog Telephone Adapters (ATAs) often have low ring voltage, less than 1 REN of ringing current, and a square wave for ringing instead of a true SINE wave as provided by the phone company".  

It looks like I'll have to give up "old faithful" and buy a newer model. I like the ability to screen calls before answering, which isn't possible just using the provider voice mail system.

(edited)

spoom2

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18K Messages

5 months ago

@HealthNut  Just one more thing, if you're also using your provider's voicemail make sure the answering machine is set to answer in less rings than the voicemail, maybe that's all it is. Just a thought. 

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