Active 1,
you have a point by prequalifying your potential prospect. They will have an idea on the price that you will charge.
I usally go out for an estimate on larger jobs. (panel upgrades, certain circuit pulls...)
If it is a new fan with wiring i have a set price if it has attic or not and the height of the ceiling as well. However, quotes over the phone might change if the job description was not accurate from the client.
I think if you try to answer your phone every chance you get and try not to bullshit the client and provide them with a service that they did not expect, then people do not mind paying more than what your competitors offer.
That is my 2cents worth.
get a call forwarding from your phone company. forward all your call to your cell phone and try to pickup every time it rings.
Edward
