BT caller ID detection and AEX400 cards

I recently thought I had resolved the “wipeout” of BT caller ID by increasing the gain on my FXO port, but tonight, a second polarity reversal hit again, this time on a “RINGBACK”.

Is there any way, under, to make the caller ID more reliable? If it gets wiped out, Asterisk treats it as “withheld”, which I do not normally allow to ring the phones.

Of course, if distinctive ring detection worked at the same time, I could use that to detect “RINGBACK” rather than relying on the caller ID name field.