I have a customer that has a dk40i. They transfer a incoming call to a external location. When they transfer it the volume is real low on both ends. Any suggestions.

There's not much you can do about low volume on a trk-trk connection with a DK. The volume naturally goes down especially if the volume of the trunks is already at a lower volume. It just gets worse.

ask the carrier to increase the DB level on the lines

Change to Centrex lines is about the only way.

Ok thanks for the info guys.