The reason that it is the #1 choice is that Tylenol is effective, inexpensive, does not require a prescription, and safer than the non-steroidal anti-inflammatory medications such as Aleve* (Naprosyn, naproxen sodium), Advil (Motrin, ibuprofen), and others.
A CLEC is a mini telephone company. CLEC stands for Competitive Local Exchange Carrier. The telecommunications act of 1996 had provisions in it designed to spark competition between local and long distance telephone carriers.
While an ISP is expected to be 99.9% reliable, a CLEC is expected to have 99.999% reliability. It must pay the proper fees, both to the government and to the ILEC. It must block out phone numbers. It must set up trunks to exchange local and long distance phone traffic between itself and the carrier.