Contracting work out wouldn't relieve the company, or the home-worker, of their legal obligations:
"21. - (1) A person shall neither use, nor instigate the use of, a public electronic communications service for the purposes of making unsolicited calls for direct marketing purposes where -
(a) the called line is that of a subscriber who has previously notified the caller that such calls should not for the time being be made on that line; or
(b) the number allocated to a subscriber in respect of the called line is one listed in the register kept under regulation 26."
Electronic Communications (EC Directive) Regulations 2003
http://www.opsi.gov.uk/si/si2003/20032426.htm
However, like all laws, the legislation will only work if people report breaches to the relevant authorities. If nobody ever reported burglaries to the police, burglars could steal whatever they liked with no worries about the consequences. Similarly,
the TPS system will only work if people report the companies which ignore the law. To do so, go here:
http://www.tpsonline.org.uk/cgi-bin/tps_compla ints.pl
Chris