NOTE: As of 6/25/2008 it appears that this api is no longer available.
From their site: AIM Phoneline is more than just a product it's a platform with a large AIM user base (43 million active users). AOL invites you to leverage this platform by developing and integrating your own products and services. AOL has created a series of APIs to help you innovate with AIM Phoneline: The Open AIM Phoneline initiative provides several interfaces facilitating the integration of partner services into the AIM Phoneline experience: Ringback Tone APIs, Auto Action APIs, Screen Name Service (SNS) API. You bring your product, service, application, or enhancement to the table, and we will give you the hooks to “plug in” to AIM Phoneline. You manage the relationship with your customers (registration, provisioning, billing and customer care) and we will work with you to promote your offer via our storefront.