In order to promote growth via SMS, you first have to require the user you already have acquired to provide your app permission to access their contacts.

In order to get users to opt-in to this permission, you have to provide them real perceived value upfront.

Therefore, I'd suggest starting with in-app A/B testing of the messaging around access to permissions prior to asking for contacts and looking at what drives the most number of opt-ins.

But just sending SMS isn't enough. You need for the recipient to want to open AND act on the link you're sending. In order to do this, you have to think about the value you're going to create for the recipient of that message as it ties back to the sender. Depending on what your app does, there might be lots of possibilities or only a small number of incentives that are big enough to inspire action.

Our app in private beta utilizes SMS in a pretty effective way to drive growth. Happy to share what we're doing and maybe share some ideas with you.