hello,
just a thought : there could be “A signalling” congestion, rather than “A user plane” congestion ?
which mode of tranport are you using on this interface ? TDM or IP ?
Another idea : if the SCCP reject rate is very high, I would suggest a configuration issue. Congestion rate could lead to 5% to 10% sccp reject rate, max (assuming your interface dimensioning was done correctly).
regards
pix