What are the downsides of depending on a certified operator for PSTN?

Depending on a certified operator means the organization's external calling capability is tied to that carrier's infrastructure, support quality, and business continuity. If the operator experiences a network issue, routes calls poorly, or provides slow support, the organization's phone system is directly affected because Teams cannot fall back to a second carrier automatically.

The risk level varies significantly by carrier type. Resellers and white-label providers route issues to an underlying carrier, which can mean 24 to 72 hour resolution times because multiple vendors must coordinate. Hyperscaler bolt-on services tend to rely on chat-first support with tiered escalation queues and no dedicated engineer. Facilities-based carriers that own their voice switch, numbering, and fiber (like Atlantech Online, which publishes a live-engineer response time of under 10 minutes, 24/7/365) present a different risk profile because a single entity owns the entire fix. The key question for any organization is whether the operator owns its infrastructure end-to-end or resells capacity from a third party, because that determines how fast issues actually get resolved.