A wireless outage that impacted the nation’s four top wireless carriers on Tuesday was caused by a technical issues at telecommunications company and Internet service provider Level 3 Communications.

According to Downdetector.com, the outage began shortly after 11 am. Eastern Time Tuesday and impacted large swaths of the country east of the Mississippi River, including much of the East Coast region. Reports of outages came from customers of all Tier-1 U.S. carriers, including T-Mobile, Sprint, AT&T and Verizon.

In acknowledging the outage on Twitter, T-Mobile CEO John Legere said the problem was caused by “issues” at a third party landline voice provider. Legere also confirmed the outage was impacting all carriers.

The issue appears to have lasted for a half hour to an hour with Legere tweeting a follow up note that Level 3 was “back to normal.” Level 3 also acknowledged the issue on Twitter during the outage and said service was restored by 11:30 a.m. ET.

In a statement released to media, Level 3 blamed the outage on an unspecified “configuration error.” However, the comapny said it is investigating to determine the “root cause” of the service disruptions.