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User Report: WPOZ Gets Positive Results With Comrex

STAC-VIP system hardware and software backed by exemplary service

ORLANDO, Fla. — In years past, we at WPOZ(FM) Z88.3 used standard broadcast phone systems such as the Gentner TS-612. While they worked fine, we struggled to get the audio fidelity that we were looking for.

A few years back, I strayed from the norm and installed a “soft phone” solution. It was part of our IP-based, business phone system, a 3Com NBX. This gave us great audio quality, but the NBX soft phone became orphaned by 3Com.


Now there are soft phone-based systems designed for broadcast, but based on my experience, I wanted a hardware-based solution that would give superior audio quality. The only way to accomplish this was to put in a system directly connected to a digital phone trunk, such as a PRI, or to digitally integrate with our office system via the IP telephony standard of SIP (Session Initiation Protocol). The second solution allowed us to share our existing PRI and give us integration with the office system.

When Comrex released the STAC-VIP, I was intrigued. On paper, it looked like what I needed. Since my 3Com office phone system was no longer supported, and given the fact that their SIP support was limited, I was pessimistic that I could get full integration between the STAC-VIP and the 3Com. However, Comrex and Broadcasters General Store ensured me that I could return the system if I could not make it work within 30 days, so we placed the order.

I installed the chassis in the rack room and connected it via AES to our Harris VistaMax system. I connected the STAC’s Ethernet port to the dedicated phone VLAN, ensuring the best network speed and lowest latency. I have QoS (Quality of Service) programmed on our network systems. It is beyond the scope of this article, but know that QoS is essential in a shared network environment for good audio quality. I installed the STAC’s control surfaces in our main on-air studio, and one in Studio B.

Initially, I was not able to get the STAC to register a SIP session with the 3Com. I went through every option and every document on the subject with no success. I contacted Comrex support. They reviewed logs and tried various settings. With no success, they asked if I could capture a network trace of a successful SIP connection with a third-party soft phone. I gathered one and sent it to them. They made a modification to their software, and after a firmware upgrade in less than 24 hours, the system connected and worked perfectly. Needless to say, I was impressed.

The chassis provides two phone hybrids, connected via either two analog lines, or a single stereo AES line. The system currently works for a single studio with both hybrids available. Comrex says it will allow the two hybrids to be split between two studios in a future software release.

The STAC allows up to six voice sessions (lines). They can be any combination of SIP connections, to one or more SIP providers, and one session of Skype. I programmed five lines to our 3Com and one Skype instance. The control surfaces can function in “screening” mode or “on-air” mode. We found them to be intuitive. Their six multi-color lights allow the staff to quickly tell the status of the call. You can drop one call at a time or use the “drop all” button to clear all calls, or keep new calls from coming in.

Even more informative is the Web interface. It shows the status of all lines and the caller ID; it allows you to type in notes about the caller and has a chat window. Calls can be answered or placed from this interface. In fact, a studio could function with the Web interface alone and do anything other than talk with a familiar telephone handset.

The Skype integration was easy to configure. I plugged in a user ID and password, and the system registered immediately. I was able to make and receive Skype calls with ease. Our station does a seasonal feature called “Christmas Around the World,” and the ease of making calls anywhere in the world, for this show, along with the superior audio quality, was ideal.

In summary, I am pleased with the system functionality, the audio quality and especially the customer support. All of my goals were met with the Comrex STAC-VIP.

For information, contact Chris Crump at Comrex in Massachusetts at (978) 784-1776 or