Most messaging apps utilize the phone’s local address book to jump start a user’s network. Typically, these apps connect you with other people who are already on the network by comparing phone numbers. They then prompt you to invite the remaining contacts in your address book to try the app — typically via SMS or email.

Ideally, when suggesting individuals to invite, you want to highlight people that lie in the cross section of “likely to be invited” and “likely to install/use your app”. But how do you identify these people when you can access only the limited information in the address book. For example, it would be highly valuable if we could see the contacts that a user has flagged as “Favorites”, but the API for iOS does not allow this.

Below, we outline a few techniques that can be used to make better referral suggestions. It’s important to emphasize that the effectiveness of these techniques depends upon individual user behavior and device operating system. There is no “silver bullet”, so your best strategy is to employ a variety of methods.