Market survey companies often use telemarketing techniques to survey prospective or past customers of a client business to assess market acceptance or satisfaction with a particular product, service, brand or company. Public opinion polls are conducted in a similar manner.
Telemarketing is often criticised as being a bad or unethical business practice as some companies use/abuse these techniques and technologies to make unsolicited calls or send unsolicited messages to people who do not want to purchase the product or service being offered and are often offended by the high-pressure sales techniques used. Such practices may be subject to regulatory or legislative controls related to privacy in legal jurisdictions. Some countries have professional direct marketing organisations that have codes of ethics that member businesses are supposed to abide by to minimise such offence.
Some jurisdictions have implemented "Do Not Call" listings, either through industry organisations or legislation, in which consumers can indicate that they do not wish to be called by telemarketers. Legislative versions often provide for heavy penalties for companies calling individuals on these listings. The U.S.Federal Trade Commission has now implemented a National Do Not Call Registry in an attempt to end intrusive telemarketing on a national basis.
To counter unethical telemarketing techniques, some people have developed a range of strategies and tactics for responding to telemarketing calls. Some technical methods rely on the weaknesses of technology that detects a call being answered by a person compared to an answering machine, fax machine or disconnected number. These technologies often simulate the behaviour of machinery that telemarketing technology rejects or otherwise confuses machinery but not human callers. As telemarketers rarely disclose their own telephone number, using caller ID can allow the targeted subscriber to identify the caller before the call is answered and the subscriber can make a decision to answer or not. Answer machines and voicemail can also be used to screen calls, as telemarketers rarely leave messages as the technology generally hangs up first. Other methods rely on upsetting the telemarketer's call script or sales pitch, upsetting the telemarketer, making it uneconomic or undesirable to call a target number, having the target number blacklisted or otherwise having the target number removed from the calling list, or not getting on the calling list in the first place.