What are some alternatives?
When comparing TelephoneLists.Biz and Lead411, you can also consider the following products
Salestools - Monitor your Linkedin newsfeed for keywords to obtain leads.
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
All The Leads - All The Leads offers probate lead lists for real estate agents and investors.
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.
MegaLeads - MegaLeads helps businesses reach out to their customer base and prospects by utilizing digital marketing and quality sales leads.
Clearbit - Clearbit provides Business Intelligence APIs