Replace Legacy PRI and CAS Circuits with VoIP Connectivity
Many older business phone systems connect to the telephone network using PRI or CAS circuits. As telecommunications providers continue retiring legacy copper infrastructure, businesses are looking for modern alternatives that allow them to keep their existing phone system.
POPP VoIP PRI/CAS replaces traditional PRI and CAS circuits with reliable VoIP technology delivered over your internet connection. The service allows your existing PBX to continue operating while helping you move away from aging telephone infrastructure.
For businesses throughout Minneapolis, St. Paul, and the Twin Cities, POPP provides a simple path to modernizing voice connectivity without immediately replacing a working phone system.
What Is VoIP PRI and CAS Service?
PRI (Primary Rate Interface) and CAS (Channel Associated Signaling) are older technologies used by many on-premise PBX phone systems.
A single PRI circuit can support up to 23 simultaneous phone calls, while a single CAS circuit can support up to 24 simultaneous calls. These technologies were widely deployed for medium and large business phone systems before SIP and UCaaS/hosted VoIP became common.
Many businesses still have reliable PBX equipment that requires PRI or CAS connectivity, even though traditional carrier-provided PRI and CAS circuits are becoming harder to obtain and support.
POPP VoIP PRI/CAS solves this problem by converting modern VoIP service into the PRI or CAS connection your PBX expects.
POPP PRI / CAS Network Map
How POPP VoIP PRI/CAS Works
Instead of delivering voice service over traditional copper circuits, POPP delivers voice traffic across your internet connection.
A POPP-provided Voice Gateway converts the VoIP service into a PRI or CAS interface that connects directly to your existing phone system.
This allows you to:
- Keep your existing PBX
- Keep your current phone numbers
- Replace aging PRI or CAS circuits
- Reduce dependence on legacy copper telephone infrastructure
- Continue using your existing phones and workflows
The service supports up to two PRI or CAS circuits for businesses that require additional call capacity.
Keep Your Existing PBX—or Upgrade When You’re Ready
For many organizations, VoIP PRI/CAS is an excellent way to extend the life of a phone system that still meets their needs.
However, PRI and CAS are most commonly found on older PBX platforms. If your system is becoming difficult to maintain, lacks modern features, or no longer supports your business requirements, it may be worth considering a migration to a modern Cloud Phone System.
A cloud-hosted system can provide:
- Mobile and desktop softphone apps
- Remote work capabilities
- Easier administration
- Advanced call routing
- Ongoing platform updates
- Reduced hardware maintenance
POPP can help you evaluate whether extending the life of your PBX or replacing it is the better long-term investment.
Voice Quality and Reliability
VoIP PRI/CAS requires a reliable internet connection, but voice traffic uses very little bandwidth.
For organizations that want maximum call quality and uptime, POPP offers an optional Voice Management Device (VMD) that can:
- Prioritize voice traffic over data traffic
- Improve call quality during network congestion
- Provide enhanced monitoring and troubleshooting
- Support automatic failover between multiple internet connections
This helps ensure your phone service remains reliable even as network demands change.
Why Businesses Choose POPP
Businesses throughout the Twin Cities choose POPP because we have extensive knowledge of both legacy phone systems and modern VoIP technology.
Whether you’re replacing a discontinued PRI circuit, maintaining an existing PBX, or planning a future migration to hosted VoIP, our team can help you identify the right solution for your organization.
With more than 45 years of experience serving local businesses, POPP provides responsive support, practical recommendations, and solutions designed for long-term reliability.
Frequently Asked Questions
Can I keep my existing PBX?
Yes. VoIP PRI/CAS is specifically designed for businesses that want to continue using a PRI- or CAS-based phone system.
Can I keep my phone numbers?
In most cases, yes. Existing business telephone numbers can typically be transferred to POPP.
How many simultaneous calls are supported?
Each PRI supports up to 23 concurrent calls, while each CAS circuit supports up to 24 concurrent calls. We will work with you to determine the appropriate number of concurrent calls for your needs.
Does PRI/CAS work during a power outage?
Like most VoIP services, phone service requires power and internet connectivity. Battery backup and generator systems can be used to maintain service during outages.
Is it better to replace my PBX instead?
It depends on the age, condition, and capabilities of your existing system. POPP can help evaluate both options and recommend the most cost-effective path forward.
Need PRI or CAS Replacement Service?
POPP helps Minneapolis, St. Paul, and Twin Cities businesses replace legacy PRI and CAS circuits with reliable VoIP connectivity while preserving existing PBX investments.