Hi, I’m using an old WMOD2 modem.
When I receive several messages, I store them in SIM.
I can erase every message individually (AT+CMGD=3), but I can’t erase all.
Every command I use (AT+CMGD=1,1 AT+CMGD=1,4) gives me error message.
How can I do to erase all messages at only time?

For an “old” modem you need to make sure that you have the corresponding old documentation - are you sure that the “delete all” command was supported by the particular “old” version of firmware in your “old” module…?