What phone features can cause problems to your dial up connection?

Several phone features can disrupt a dial-up connection, including call waiting, which can interrupt the data transmission if a call comes in. Additionally, voicemail systems can create issues if they attempt to take over the line. Other features like fax machines on the same line can also interfere with the modem's ability to establish a stable connection. To maintain a reliable dial-up connection, it's best to disable these features when using the internet.