Syniverse has blamed an international roaming outage which affected AT&T, T-Mobile, and Verizon customers on a misconfiguration error.

The outage caused disruption for users from June 26 to June 29, until the issue was resolved.

In a statement, Syniverse, which provides roaming services for all three carriers, said that the disruption has been fully resolved.

"As we previously shared, the root cause stemmed from misconfiguration errors at a peering partner outside of our network. It was not the result of a cyber attack," said Syniverse.

The company explained that the global network became flooded with error messages causing a near-infinite loop called a "signaling storm."

"This necessitated a blocking of a very limited number of peering partners who were producing excessive error loops and an upgrade of network capacity. We have now ensured safe performance and brought all peering partners back onto the network with full service restored," the company said.

Syniverse noted that it will take further steps to prevent such incidents from happening again.

The outage led to many users reporting issues accessing apps such as banking, maps, or the ability to order a taxi.

AT&T has said it will issue credit to any customers who were impacted during the outage.