According to the ATC, the own number can be displayed with the command AT+CNUM,
but only in case ithe number s stored on the SIM card by operator.
It is possible also to save your own number on the SIM card, however such functionality sometimes is blocked by MNO.
For most cases the query is not working, for most MNO prefer not to store phone number on the SIM;
if your MNO doesn't block this function, you can write on your own.
Here is an example about how to do it:
at+cnum?
+CME ERROR: unknown
at+cpbs? - display the active phonebook storage
+CPBS: "SM",250,250
OK
at+cpbs=ON - select the active phonebook storage to MSISDN list
OK
at+cpbs? - display the active phonebook storage,
+CPBS: "ON",0,3 - MSISDN list is empty
OK
at+cpbw=,"+48723976327" - enter your own MSISDN
OK
at+cpbs? - display the active phonebook storage,
+CPBS: "ON",1,3 - MSISDN list has one item
OK
at+cpbr=1 - reading MSISDN list, position 1
+CPBR: 1,"+48723976327",145,"" - own MSISDN
OK
at+cnum
+CNUM: ,"+48723976327",145 - own MSISDN