How effective is telemarketing?

In some cases email campaigns are more effective. As it gives them basic info about the product we are trying to sell. As well as they can consult with their manager/partner about their necessity and...

effective in

Telemarketing is marketing conducted over the telephone. Most telemarketing calls are "cold calls," meaning the recipient of the call has not requested that the telemarketer contact them....

Both, to have effective communication you need to be a good communicator but you also need to listen to what the other person has to say.