From The Apple Wiki

CoreTelephony is the iPhone framework used for high-level cell modem interaction. It handles SMS, MMS, phone calls, etc. It is written in C, C++, and in 3.0, Objective-C portions were added.


In order to use CoreTelephony, you need to set up your build environment to link against it.
You also need a set of header files, which can be obtained by using the class-dump tool on the framework.

C functions/types

 typedef struct __CTSMSMessage CTSMSMessage;
 void*                CTTelephonyCenterGetDefault();
 void                 CTSMSMessageSend(void*,CTSMSMessage*);
 CFStringRef          CTSMSMessageCopyAddress(void *, CTSMSMessage *);
 CFStringRef          CTSMSMessageCopyText(void *, CTSMSMessage *);
 CTSMSMessage*        CTSMSMessageCreate(void*,CFStringRef number, CFStringRef name);


The ObjC parts are much easier to work with because of the magic of class-dump. The only work I've done is getting an SMS message sent out. This can be accomplished in one line of code:

 [[CTMessageCenter sharedMessageCenter]  sendSMSWithText:message serviceCenter:nil toAddress:number];

where message and number are NSStrings filled with the correct data.

Experimental code to listen for incoming SMS

 static void callback(CFNotificationCenterRef center, void *observer, NSString* name, const void *object, NSDictionary* info) {
 fprintf(stderr, "Notification intercepted: %s\n", [name UTF8String]);
 if([name isEqualToString:@"kCTMessageReceivedNotification"] && info)
   NSNumber* messageType = [info valueForKey:@"kCTMessageTypeKey"];
   if([messageType isEqualToNumber:[NSNumber numberWithInt:1/*empirically determined!*/]])
     NSNumber* messageID = [info valueForKey:@"kCTMessageIdKey"];
     CTMessageCenter* mc = [CTMessageCenter sharedMessageCenter];
     CTMessage* msg = [mc incomingMessageWithId:[messageID intValue]];
     NSObject<CTMessageAddress>* phonenumber = [msg sender];
     NSString *senderNumber = (NSString*)[phonenumber canonicalFormat];
     NSString *sender = (NSString*)[phonenumber encodedString];
     CTMessagePart* msgPart = [[msg items] objectAtIndex:0]; //for single-part msgs
     NSData *smsData = [msgPart data];
     NSString *smsText = [[NSString alloc] initWithData:smsData encoding:NSUTF8StringEncoding];
     fprintf(stderr, "SMS Message from %s / %s: \"%s\"\n",[senderNumber UTF8String],[sender UTF8String],[smsText UTF8String]);
 int main(int argc, char **argv)
 NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 id ct = CTTelephonyCenterGetDefault();
 CTTelephonyCenterAddObserver(ct, NULL, callback, NULL, NULL, CFNotificationSuspensionBehaviorHold);
 // Start the run loop. Now we'll receive notifications.
 [[NSRunLoop currentRunLoop] run];
 [pool drain];
 printf("Unexpectedly back from CFRunLoopRun()!\n");
 [pool release];