We need to know a little bit more about your setup. Where the call is coming from and what type of network setup you have at your location. This might give us a better picture of what is going on.
I have a Cisco AS5400 gateway that is in the US that is connecting to a Quintum A800 in Asia. I have been receiving this message any time I send a call to the Quintum. I get a call rejected (21) on my Cisco when I make the call. Reading the Quintum manual this says that the unit is configured correctly and that when I look at the event log on the Quintum I should be able to see where my proble is. Well the problem is I get this massage when the call hits the Quintum.