how to use CoreTelephony framework

can any one help me in understanding CoreTelephony framework by telling among any one g开发者_如何学运维iven below

• any simple apps example that is using core-telephony framework

• i am able to add core-telephony framework but not able to import any header file of it

although they exist in frameworks that i have added

any help will be appreciable as soon as possible.

Thanks

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CoreTelephony files imported using <> not ""
For example:

#import<CoreTelephony/CTCarrier.h>