Telemarketing still works very well regardless of TPS especially for B2B contract cleaning services. If you undertake your own campaign any data you buy should initially be TPS scanned for barred numbers it will also need rescanning every 28 days, again your supplier should be able to do that. An excellent source of data and screening can be provided by
http://marketingfile.com/I disagree with Lee, you will not receive abuse if you approach the campaign in the right way, telemarketing is a skill just like any other profession and if you are prepared to put the time and effort into learning you could conduct your own campaign and have a relatively high degree of success.
I have recently started a blog to help people understand and learn more about telemarketing, it’s early days but watch this space...
http://www.kmg-s.com/blog/Of course you could also engage the services of a professional telemarketing company and let them take the strain.
Hope this helps.