Read and write SIM records

[mdecaso]

I am trying to access and Modify SIM content from the Operating System. I am working with a dual line twin card and want to change between one line and other by code.

I am using SIM Manager functions (SimGetRecordInfo, SimReadRecord and SimWriteRecord).

Does anybody know where I can find the structure which contains the two imsi data? I think it is not on the EF_IMSI (6F07), isn't it?

I have been able to read the EF_SPN (6F46), which contains the words Work or Home.
I have been able to read the EF_IMSI (6F07), which contains in Hexadecimal the current IMSI.
I have not been able to read the EF_MSISDN (6F40). Does any body know how can I do it?

I have also tried to write on these records (so that the current line will be changed) but I have got a "Security Failure". Have I got permission to modify this kind of records?

Thanks in advance