The IRS is strongly encouraging all businesses to sign up with the Electronic Funds Tax Payment System (EFTPS) that is made available by the US Treasury.
When calling, be sure to have the ACH number from the account that you pay your taxes from handy. This is the 9 digit number on the bottom of your check. Also, have your bank account number at the ready.
The activation process over the phone takes about eight minutes. Doing it online takes six minutes. If you already have an EFTPS Personal Identification Number (PIN) that came in the mail I suggest activating by phone. The system set up by the IRS appears to be more efficient when doing activation over the phone. There is actually an 18 digit enrollment number. When you activate over the phone you will receive only the last 8 digits. Be sure to write this number down because you will need it for setting up your online account. Setting up the online account can be done on the same call but it sounds like there is a connection to a different system.
There have been scams involving unscrupulous people using the cover of EFTPS for trying to extract personal information including tax ID numbers. Be confident that you are dealing with the correct party before giving personal information over the phone or via the internet.
Be sure to contact 1-888-434-7338 if you have any questions about EFTPS enrollment.