John, Don't know of any sites but if you can do multi-zone audio you can and should be doing phones and phone systems. When I started my biz I also stayed away from phones, now phone systems are an important part of my product mix. Learning phones and computer network cabling opens another profit center with structured wiring. Talk to the guys at Capitol Sales about getting started, probably the best tech support you will find for phones.
www.capitolsales.com
Good luck
Deco