KC,
Is this a problem that occured from day 1, or is it somthing that happened after time?

Don't take this the wrong way but I think you are handling this problem the wrong way, here is what I would do. (I can't afford to keep running back and forth, plus it does not make for a happy customer. This is why I would do it this way).

Buy a new phone and base and install it, if all works ok then you are done, if not then it is an enviormental problem, again you are done. If the problem is not solved with the new phone the customers choices are as follows.

1. You can refund them the money you charged for the phone and they will not have a cordless.
2. They keep the phone and live with the dead spots (again enviormental issue)
3. You install an analog card, credit them the difference for the cordless you installed. Have them buy an off the shelf cordless that they can use off the analog ports. This is a good option for them because they can try as many phones as they want till they find one that works at their location. Just tell them to keep the box and all the papers so if they are not satisfied they can return it and try another phone.

When I sell anything cordless (headsets or phones) I tell the customer I cannot guarentee you will be happy, it is the nature of the beast, I can have a cordless phone that works great at one location and is a dog at another. Enviormental conditions will dictate how good a cordless device will work at a particular location, unfortunetely I have know way of knowing until we install one. Most customers will be able to relate to this since they have had experiences with cordless phones at there homes.

I will offer to let them try one for a week or so and if they are satisfied then we will install the others (if they have more than one phone or wireless headset). If they are not than I remove the phone (or headset) and do not charge them.
I then offer them the analog card option.

I hope this helps you out in the future.

P.S. I just became an ESI dealer, really looking forward to getting some of these systems installed.

Walter

http://www.valentinesystems.com