Android 4.4 KitKat debuted last week with a smart new phone dialer that matches incoming calls to businesses with a Google Places listing, but that’s just the start of Google’s plans for caller ID. Early next year the search giant plans to link Google+ profile pictures to mobile phone numbers. Google accounts that have a verified phone number will be automatically opted in and linked to the associated Google+ account. In reality this means that anyone using Android to call, or receive a call, from a number linked to a Google+ account will see a profile image automatically without the need to have contact information stored.
While the functionality improves the dialer experience for Android 4.4 and above, it's bound to generate some privacy concerns over the default opt-in. However, Google+ users need to have shared a profile image and mobile number previously in account settings, so it won’t be automatic for every user unless a phone number is associated with the account. Google’s initial caller ID improvements for businesses are already live with Android 4.4, but the Google+ photo integration is "coming in early 2014" according to the company. If you want to prevent the photo sharing then you simply have to disable the "help people who have your phone number find you on Google services and connect with you" option in Google’s account settings.