I also write (or wrote, up until recently) telecom software and, while I like Actors (certainly compared to monitor-based concurrency), I agree that they aren't really the silver bullet. I spend a lot of time thinking about concurrency and I've come to the conclusion that the dificulties of concurrency all come from the fact that everythings manual - the programmer has to carefully think about how everything fits together, or risk all kinds of problems: deadlock, inconsistent data, bad parallelism etc.

The Actor model certainly makes things easier, but doesn't work as well for some problems. Its also still a manual task. STM improves monitor-based systems by alleviating the task of carefully placing locks around critical sections of code, but you must still determine where to place the transactions and this can still be a big task. So far, the only model that, IMHO, lends itself to implicit programmer-free concurrency is dataflow. Ultimately, I think we need a language that exposes all three models (monitor, actor, dataflow) as language primitives, handling it implicitly and transparently where possible.