i am observing lots of Connection refused messages after Paging response with refusal cause SCCP user originated. these are all for Terminating calls only. happening for one BSC which is already facing air and a interface congestion
Might be that maximum number of SCCP connections in A-interface exceeded. Or theres not enough space for SLR/DLR session identiriers from MSC side for SCCP-connection establishment.
You wrote that it’s only in Term-call scenarion. MO-call works?
Whats the cause of congestion: huge traffic or some configuration failure of A-interface?
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).