Hi anyone and everyone
I've bought a couple of Grandstream HT-488 to use with my Freespeech account. This features 1 FXS and 1 FXO port for call forwarding between VoIP and PSTN. As well as PSTN pass-through so I can make PSTN or VoIP calls from one handset.

I'm getting a couple of problems. I'll just deal with the first here.

I get line echo when I make a PSTN call. I suspect it's to do with one, or both of two settings in the FXS port. These are:

1) FXS impedance, which I have set at CTR21 (270 Ohm + 750 Ohm || 150nF). Does anyone know what I should choose?
2) Oh hook voltage 36V. I guess this depends on Eircom. Again any suggestions on what it should be.

And 3) I have Caller ID set at ETSI-FSK... should it be ETSI-DTMF does anyone know?

If I can get these settings sorted, I can see if addresses some of the other issues experienced by callers.

Hope someone out there knows

Regards
David Marshall