Comdial (Vertical) Manuals for DX-80 and DX-120 Phone Systems.
Page Updated: September, 2026
Here you will find Comdial manuals for the DX-80 and DX-120 (Which became Vertical.) phone systems along with the manuals for the Edge telephones. For other Comdial phone system manuals see our Comdial Phone Manuals 1. (Note: Some of the DX-120 systems and telephones will display the manufacturer's name Vertical. These small business telephone systems were digital, see below for more information about the change over from Comdial to Vertical.)
The Comdial DX-120, first introduced in 2007, reached its end-of-life in 2014. Vertical Communications, who acquired Comdial, introduced newer phone systems to replace the DX-120, like the Vertical SBX and the Vertical Summit. The SBX line was discontinued by Vertical back in 2017.
The Comdial DX-120 is a legacy key service unit (KSU)/PBX phone system
designed for small-to-medium businesses, sold by Comdial and later
marketed under the Vertical brand once Vertical Communications acquired
Comdial. It is expandable up to 16 CO (loop-start) trunks (lines), 24
digital lines (T1/ISDN-PRI), 88 extensions, and 8 voicemail-processing
channels. It typically pairs with the 7261-00 Edge 120 executive phone.
Most cards, phones, and accessories are interchangeable with the earlier
DX-80, making it easy to source refurbished parts.
Feature-wise, the
DX-120 ships with a nice feature set that previously required high-end PBX
systems: built-in Caller ID, Direct Inward Dialing (DID), Uniform Call
Distribution (UCD), "Meet-Me" conferencing, fax detection for routing
faxes through the system, SMDR call accounting, paging, and music on hold.
It requires an optional module for an auto attendant.
If you are considering replacing either of these legacy systems, click the link at the bottom of the page to receive no-obligation quotes tailored to your needs and budget.
Comdial (Vertical) DX-120 and DX-80 PBX Guides
DX-80 Telephone and Tech Manuals
Comdial DX-80 Tech Manual-
Install and Maintenance
Comdial DX-80 Tech Manual- Programming
Comdial DX-80
Supervisors Guide
Comdial Edge DX-80 Digital Exec Phone Users Guide
DX-120 Telephone and Tech Manuals
Comdial-DX-120 Install and Maintenance Manual
Comdial DX-120 Programming Technical Manual
Edge 120 Digital Executive Phone Users Guide
Need a Replacement DX-80 or DX-120 Telephone?
If you're adding an additional telephone or need to replace one on a Comdial / Vertical DX80 or DX120 you can find these digital phones at excellent prices (with free shipping possible).
Comdial DX80 phones are the 7260-00 model (digital handset). For a great price from a trusted source: Comdial DX-80 Telephone
The Comdial DX120 system uses the 7261-00 phone model (30 button digital handset): Comdial DX-120 Telephone
Upgrading From an Old Comdial System
The DX-120 is now more than a decade past its 2014 end-of-life, which
makes it genuinely dated. The hardware runs on early-2000s digital/TDM
architecture with no native VoIP integration, and the manufacturer no
longer produces parts or provides formal support. Businesses that still
have these systems are increasingly dependent on a shrinking pool of
refurbished spares and aging technicians who still know the platform.
If your goal is a more recent on-prem PBX, a realistic upgrade path is
to stay with Vertical and its newer SBX and Summit KSU platforms, which
are IP-capable and support the same SIP trunks and modern endpoints. Or
move to a current-generation on-prem solution like a hybrid digital/IP
platform that gives you the control of premise-based ownership with SIP
trunking, hosted failover, and easier remote administration.
Keyvoice (Debut)
Comdial Key Voice Debut & Lite Supervisor Guide
About Comdial and the DX120 & DX80
Comdial Corporation was taken over by Vertical after it declared bankruptcy.
The digital DX phone systems were very popular at the time for small businesses,
dependable and with enough features to satisfy most consumers. They were then continued
by Vertical and sold through vendors. Vertical branded the systems within their
own name and logo. The DX-120 systems can be found with both the
Vertical and Comdial names on them, as well as the popular DX-120 telephone handset, the
7261. Regardless of the brand name on the phone they will work with the DX-120
PBX.
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