There have been several reports over time that certain cordless telephones can interfere with the Vonage service and the ATA-186.
If you are having problems and have a cordless, it is suggested that you consider experimenting without the cordless, to see if it is causing the problem.
It is also reported that this can occur with corded phones as well. The real problem is where the base of the phone is too near or on the ATA. Separating the ATA from the phone usually resolves the problem
It might be possible but it can present several problems. Altering your home wiring (at your phone jacks) may be necessary, and you may experience problems with some (or all) of your phones not ringing, and possibly risk damaging your phone or VoIP adapter.