First response
The machine that gets the house working again
When a main line stops, the rooter is the tool that comes off the truck. A steel cable is fed in through the cleanout with a cutting head on the end, spun under power, and advanced until it reaches and breaks up whatever is stopping the line. Flow returns, the house is usable again, and the whole thing usually takes an hour or two. For a large share of stoppages that is the complete and correct answer.
What the cable brings back is also the diagnosis. Root hair on the head means roots. A greasy grey coating means the kitchen side has been building for years. Grit and sediment suggests a low spot holding water. Nothing at all, with the cable stopping dead at a fixed distance, usually means something structural, and that changes the conversation entirely.
The honest limitation is what a cable does to a pipe wall: nothing. It bores a channel through an obstruction. On a one-off blockage that is enough, because the pipe underneath is fine. On a line that has been coating for decades or admitting roots through an open joint, the hole closes again on its own schedule, and the interval between visits is the useful measurement.
So the standard here is to clear first, because you need a working toilet tonight, and then be plain about which of those two situations you are in. That distinction is worth a camera run, and it is what separates a repair that ends the problem from a service call that repeats forever.