How can upgrading my business phones or internet service disrupt my credit card processing?

Most of the countertop POS terminals (POS = credit card processing machines) being used at small businesses operate on a conventional analog phone line. These POS terminals often use a dial-up modem, very similar to the ones used in fax machines. If the analog, ‘dial-up’ phone line is eliminated, your POS terminal loses its ability to connect to your merchant service network. If the terminal cannot connect, sales cannot be approved by the cardholder’s bank. The ability to process credit cards would be lost.