He isn't spamming. It's the shitty, outdated version of the SMF forum software that does that. It appears to the poster that their post wasn't received, so they re-post (over and over).
But, to answer the question, there is no such recorded message generated by those carriers. However, telephone service providers often establish call time-out intervals. This is to protect their network from leaving calls set up that are actually dead, but the system didn't detect a hang-up. For example, Google Voice's time limit is three hours. Callcentric allows the user to specify the time limit, up to eight hours.
However, conference calling service have their own limiters, which will not only hang up after some excessive amount of time, or if no audio is detected after some shorter amount of time. If you are sitting on your butt on a long conference call or on hold to a toll-free number, un-mute your phone and make some sort of sound periodically, to reset the no-audio-detected time-out.