Salesforce, SugarCRM, ZoHO ... if you can afford them. Anything else is too limited meaning you must conform your business to the product as it lacks versatility to adapt to your specific niche/process - unless you are an excellent programmer with extensive knowledge of access/.Net/database/visual basic/etc. Good luck, personally if I had the money Salesforce looks incredible and integrates with other business process and PBX (such as Invox/PBX+)
This is CABL.com posting #307846. Tiny Link: cabl.co/mbsfq