Grandstream HT-701 High Pitched Noise

[Steve P]

I've just got setup with my Fongo service and have a Grandstream HT-701 device. I'm getting a high pitched noise on the line that can only be heard on my end, not the person I talk to. Turning down the volume on the phone does not remove the issue, just how loud the noise is. Can anyone assist with this?

Thanks,

Steve

[dibsmft]

Is the HT-701 near some other electrical device such a power supply transformer, cordless phone etc. How high pitched is the noise?

[Steve P]

No, just near the router on my computer desk. I even tried switching the cable, updated the firmware and tried it on a different router upstairs. It odd, because it seems to be worse at night.

[Steve P]

No, just near the router on my computer desk. I even tried switching the cable, updated the firmware and tried it on a different router upstairs. It odd, because it seems to be worse at night.

[Steve P]

Update:

So I finally got around to contacting Fongo support via telephone. They are shipping me a new ATA. I'm not sure if this is a known issue or not but basically just told them there was a high pitched noise and the tech on the phone said she could hear it too. I'm wondering if it is a known issue since they didn't ask me to troubleshoot, just said they were going to replace. I will post an udpate once I get the new ATA to see if that resolves the noise issue.

[FONGO_steve]

Update:

So I finally got around to contacting Fongo support via telephone. They are shipping me a new ATA. I'm not sure if this is a known issue or not but basically just told them there was a high pitched noise and the tech on the phone said she could hear it too. I'm wondering if it is a known issue since they didn't ask me to troubleshoot, just said they were going to replace. I will post an udpate once I get the new ATA to see if that resolves the noise issue.

Confirming from our side that it definitely is not a known issue. The Grandstreams are very reliable and problem free ATAs. It was likely just a defect in the unit which was missed or not occurring when it was configured and tested here.

[Steve P]

Yup, the unit was replaced with a different model. All is good now.

[mcclaud]

Beware of units from ebay I bought two of these Grandstream HT-701's from ebay advertised as new at only 35 CA. bucks including shipping as it turns out they both have that high pitched noise problem, I suspect that this is a ht-701 failure and that the ebay supplier may have access to defective units perhaps after they are returned.

Fix for the problem, funny thing is I tested the voltage on the the ring (red wire) output of analogue port and noticed it was +48volts rather than -48volts respect to ground, this is not standard for actual PSTN lines or pbx's i have worked with (pc linux box,nortel PBX) though it may be standard for the ht-701. Anyways I decided to reverse the polarities that is switch the green and red wires and the high pitch winding sound stopped!! It should be noted that this sound was more pronounced on my Panasonic portable phone than my basic hard wired phone and most likely different portable phones which use different circuits may react to this this defected ht-701 in different ways.

BTW the high pitched noise doesnt seem to be a result of any particular interference as I have tested both defective units in different houses even one in a basement with almost no electromagnetic radiation and the high pitch is consistently present.

[46jimbo]

Hmm. I also bought 3 HT701's from the same eBay seller and have no problems.

[mcclaud]

Like I said it may be all ht701's do this with certain Panasonic portables, I have two panasonic base stations and two ht701's all combinations result in the high pitch noise.
it did fix it to revers the polarity also recently updated the firmware and found a more straight forward fix ; just turn the gain down to 12DB in the ata, no more winding noise.