You only have authority to call someone in their home if they have given you permission to do so. This permission can be given as part of a contract, or by a customer or prospect providing their home telephone number on a website or reply form. If you do call someone in their home without their permission, you could do irreparable damage to your brand and business.
The exceptions to the rule are charities, political parties and market research companies.
If customers have given you their home telephone number you can call to make them an offer, conduct your own research or just thank them for their custom. But you must respect their privacy if they ask to be taken off your telemarketing list.
Telemarketing could be defined as the organised use of the telephone for communication purposes. It is now a 'mainstream' media recognised for its ability to let you quickly contact customers and prospects, or as a conduit for them to contact you. Companies in all service industries are setting up call centres to offer support for advertising campaigns and provide service to customers. By qualifying customer or prospect details, you'll minimise wasting money on wrongly addressed mail or unsuccessful cold calls by expensive sales representatives.