You created a new interconnection with MCM Telecom and after executing tests, you have identified that SMS-GW is answering with the following - “ESME receiver reject message error code”. You want to know why SMS-GW is blocking the incoming SMSs and which one of the rules is causing it.
Messages might be rejected from MCM due to a misconfigured AOR (Application Originating Routing) rule. A common mistake in the AOR rule is the True/False flag setting (T/F) for the AutoBlackList service.
If you click on the square highlighted on the image below, it toggles between F and T (False and True).
Our recommendation when creating rules, applications, or anything else which is similar to an existing one, is to create the new one based on a COPY of the existing one. You may right-click on the existing rule/application and select COPY as seen on the image below. Then a new one is opened carrying the same settings as the existing one, so you can simply adjust the differences.
If this was not the cause of your issue, contact support for further assistance.