AT&T is winding down a 15-year web alliance with Yahoo, as the fallen internet giant eyes rival operator Verizon among potential acquirers of its core assets.

Smaller internet firm Synacor said it had been chosen by AT&T to deliver a portal services contract worth in the region of $100 million per year, once it is fully deployed in 2017. Early services will start in Q2 2016, said the firm, with broader services scheduled for deployment in Q4 2016.

“We have agreed to have Synacor manage our next-generation att.net portal, AT&T-branded applications, and search,” the operator told the Wall Street Journal. Yahoo will continue to host email for AT&T subscribers, though a source said that this represents a fraction of its previous business with the operator.

Yahoo is currently in talks with various bidders about buying its core assets, with AT&T’s major rival, Verizon, having emerged as the leading bidder.

Synacor will develop and manage mobile and desktop portal services for AT&T, as well as providing content and monetisation through search and advertising. The revenue from search and advertising will be split with AT&T.

Another long-standing Yahoo deal is set to end in 2017. SoftBank currently pays about $200 million annually in licensing fees for Yahoo Japan, of which Yahoo is still a stakeholder. About half of those fees expire in August 2017, though a separate licensing deal with the Yahoo brand has no expiration date.