The AT Commands Interface Guide description of AT+CSCA is incomplete - it does not describe the query command at all, and omits the optional parameter from the set command:
Command: AT+CSCA?
Response: +CSCA: ,
is not documented (it is the Type Of SCA).
Hi,
should you mention which version of the document is affected?
In the one I have (The one from Firmware Release version: B62e) does include values 145 for international number and 129 for national number as values for the tosca parameter and includes the query command.
Best Regards,
Jan
Yes, I should! 
It applies to both 6.57 and X51a.
The documentation is now wrong:
The red-highlighted comma is, clearly, spurious
Similarly: