Paging & Intercom: Analog vs. IP
Jim Tchinski, EET, CTS, NET+, NICET | Technical Solutions Engineer
What are the differences between analog and IP paging/intercom systems? First, let’s look at the differences between Intercom and Paging systems. Think of these as two different systems. Paging is a way of mass notification, usually to a large group of people; it is one-way communication so people can hear the message but cannot respond to it. Intercom is two-way communication so people can hear the message and also respond back to the person initiating the call, with the speaker acting as the microphone.
Analog paging systems can be designed with one main amplifier feeding many speakers that can be daisy chained in a loop, or there can be multiple home runs from the speakers back to a single amplifier. Analog paging systems can also be designed in a distributed configuration with amplifiers spread out in a building providing local amplification per area. This would require a single speaker run from the main amplifier to each distributed amplifier, and a transformer to connect the signal back into the input of that amplifier.
Analog intercom systems consist of a single headend point with multiple cable homeruns from the classrooms, or other such areas. Intercoms typically have mini amplifiers on circuit boards feeding each speaker. This allows the capability of calling each speaker individually for two-way conversations in a room. Intercom systems can also be laid out in a distributed design with a category or network cable running between closets. The speakers are then connected to small 16 or 32 port interfaces thus eliminating the need for long speaker runs.
When considering an IP paging or intercom system, the first question asked should be, “Will the end user want the devices on their ethernet network?” Installing this system will involve someone with some IT knowledge to connect the headend device and speakers to the network, assign IP addresses and configure the network. The design of IP intercoms and paging systems is very similar. Each will have a PC or a master box with a microphone connected to it and a network connection. The master box is programmed by a PC and then runs by itself with the PC removed. The speakers will each have a network connection to them from a local network closet and are typically powered over the network cable by PoE (Power over Ethernet).
How does one know which system is best for their facility? Here are some pros and cons of each system to help in this process.
- Good solution for replacing an old, existing analog system
- Inexpensive speakers
- Inexpensive cabling
- No IT knowledge necessary
- Once the system is installed network changes will not affect the system
- May require long cable runs if the system is not in a distributed design
- “It’s not IP” so standard category structured cabling is not used
- Once the speakers are wired, changing zones that were not initially designed requires re-cabling
- Cannot create new “on the fly” paging zones
- Good system for new construction
- “On the fly” paging zones can be created at any time since each IP speaker is a zone
- Speakers can be monitored for failures by network software
- Systems use inexpensive category ethernet structured cabling so there is not a separate intercom cabling plan
- Not a cost-effective solution for replacing an existing analog system
- System install, setup and service require IT knowledge
- When the network goes down you may lose paging capabilities – important for emergency and lock-down situations
- When there are changes on the network it could affect the paging system