Purchased BT6500 Phones line crackled and breaks up

SOURCE: Excessive crackling noise on house phone.

It sounds like you might have a problem with the filter, if you get noise once you plug into the ADSL box. Unless the ADSL box has a filter in it.

The ADSL box cannot be filtered but the phones must be filtered. Try another filter. You should be able to get one from the ADSL provider or buy one in a store or online.

The green white wire is the third pair ow wires. I am guessing that it is on your station wire side and is not in use. Try the filter first.

SOURCE: I have a Panasonic KX-TCD220E

I had the same problem with KX-TCD220E and BT line. Cured by changing the DSL filter.

SOURCE: really bad crackling on line

Without the make and model of the phone unit, I would guess you are suffering from interference if you're using a cordless phone system.

If you are, move the base unit to a room that doesn't have appliances, wifi, or computers and check to see if that removes the static.

SOURCE: Had a bad electrical storm.

The damage is not to the phone line it is to the phones. Unfortunately this is very common with powered phones as they are almost never kept on surge protectors and are very fragile. You will need to purchase a new base station to use with existing phones.

SOURCE: We have two newly purchased

You can't pick it up on another unit unless it is transferred from the original phone. I HATE that about this system. I have a question - we are trying to use a second base unit and are having a terrible time getting it to work right. Is it possible to use more than one base unit?