Receiving normal SMS messages works fine. I see a "+CMTI: "ME", <idx>" notification on the Virtual COM port. I can then read the message with AT+CMGR and find it in the AT+CMGL list.
However when receiving a WAP push message (that is an MMS notification), nothing is printed on the Virtual COM port, and nothing is to be found when executing AT+CMGL=4. If I hook up USBPcap+Wireshark while receiving the WAP push, I can see that on some other interface (the interface used for internet?) I see some binary data that includes the full WAP push SMS message, so it is apparently received by the module.
Before I firmware upgraded to Quectel version BG96_Firmware_Release_Notes_V0207_01.016.01.016, I could see some bogus "+CMTI: "ME", -1" notifications when the WAP push arrived, but now after the firmware upgrade nothing is shown anymore. According to the release notes it fixes a bug with description "Fixed the bug that unexpected URC “+CMTI: -1” reported when module received WAP push type message.".
Putting in the same SIM card in an old D-Link DWM-157 modem and then hooking up the Virtual COM ports, I can now clearly see the WAP push messages coming in with +CMTI, as well as the message can now be found with AT+CMGL and read with AT+CMGR.
So for some reason TRM250 seems to discard incoming WAP push messages. Is this a bug?