I remember some ISPs allowing you to "shotgun" two 56k modems for double the speed! Like some other commentors I also fondly remember ISDN. Overall I found it

I remember some ISPs allowing you to "shotgun" two 56k modems for double the speed! Like some other commentors I also fondly remember ISDN. Overall I found it to be finicky. Sometimes one channel would just drop, even if a phone call wasn't coming in. And, in order to use a traditional analog phone with your ISDN line, you needed a special powered "TA" adapter or the phone wouldn't ring when a call came in.