Over the last day or so, customers of the big three US mobile carriers — Verizon, AT&T, and T-Mobile — who are using data roaming internationally have complained about an inability to connect and make calls. Complaints about connection problems have spread across social media for hours, with little response from the carriers.

According to T-Mobile vp of corporate communications Tara Darrow, “…we’re one of several providers impacted by a third-party vendor’s issue that is intermittently affecting some international roaming service. We’re working with them to resolve it.”

In an email sent to The Verge, AT&T spokesperson Keoni Holoman also explained that the issue is apparently linked to an unnamed third party:

The AT&T network is operating normally. Some customers traveling internationally may be experiencing service disruptions due to an issue outside the AT&T network. We’re working with one of our roaming connectivity providers to resolve the issue.

That won’t help anyone get connected, but the companies are aware of the issue. A tweet from Verizon’s support account on X says, “Our teams are actively working with local providers to resolve the issue” of calls not connecting for people traveling abroad.

Update, June 27th: Added statement from T-Mobile.