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ISDN the right choice

Learn if ISDN Centrex is the right choice for you.


Items to consider when making a choice

  • Would like the capabilities and features of Electronic Key Line Centrex but are not on a DMS100 switch.
  • Need high-speed Internet access for faster transfer of audio, video and high-resolution graphics
  • Use computer telephony integration (CTI) to simultaneously look up customers' information as they call
  • Use desktop videoconferencing and other advanced applications requiring high-speed data transfer and extremely reliable voice communications
  • Need remote PC access to tie together remote offices and telecommuters into a simplified network to share files and mission-critical applications

How will ISDN Centrex benefit me?

  • Faster transmission speeds – ISDN can handle larger files faster and can transmit approximately 80 pages of data in less than a minute. ISDN can also support complex graphics and videoconferencing. ISDN vs. Analog Speed Comparison
  • Faster call processing – ISDN frees up lines faster so you can receive and manage more phone calls. It's perfect for call centers and other businesses that handle many calls throughout the day.
  • Simplified, standard interfaces – ISDN is compatible with other types of access lines and with various products throughout the SBC region, so it's easy to add to any existing Centrex system.
  • Fewer transmission errors – When compared to analog networks, ISDN provides increased reliability for data transfers. This means you'll spend less time re-sending data.
  • Opportunity for usage-free calling – ISDN Centrex allows for easy communications between all your Centrex lines. In many cases, multiple locations can be tied together to create an entire usage-free network.
  • Increased functionality – ISDN Centrex offers a host of standard features that are optional with Basic Centrex or ISDN-Direct.

Features of ISDN Centrex and their benefits to you 

FlexibilityYou can add ISDN Centrex one line at a time and switch your line types from Basic Centrex to Electronic Key Line Centrex to ISDN Centrex at any time.
High-speed transmissionISDN Centrex offers accurate digital data transmission of voice, circuit-switched and packet-switched data at speeds up to 128 kbps. You can move 80 pages of data in less than a minute.
Integrated voice, data, and video through a single pair of wiresYou no longer need a second or third line for data communications.
End-to-end digital connectivityYou benefit from virtually error-free data transmission, giving you a clearer and cleaner signal with built-in error detection and correction.
Packet switchingThis transports data efficiently by enabling many users to share the same network resources.

ISDN Centrex in your office

Do I need to purchase extra equipment?
Yes. ISDN lines require the purchase of ISDN equipment, including the ISDN telephones and terminal adapters to connect your phones to your ISDN lines.
  • Tone Commander 8610, 8620, and 8810 Multi-line terminals with advanced automatic setup capabilities
  • Tone Commander 6210 and 6220 Multi-line terminals with advanced automatic setup capabilities.
  • Fujitsu 9912 and 9924 Full key system functionality without the hardware and wiring associated with key systems or PBXs.
  • Tone Commander NT1 Network Termination Units Units to connect your ISDN phones to the SBC network.
Can I use Centrex Mate with ISDN Centrex?
Centrex Mate is a standard feature of ISDN Centrex. Centrex Mate allows you to customize your office's Centrex system from your desk.

Can I use voicemail with ISDN Centrex?
Yes. Voice Mail Service (VMS) makes your office more efficient. With VMS, you'll never miss a call.

What if I'd like to upgrade?
ISDN Centrex is an extremely versatile and technologically advanced system. But if you need more functionality, you should check out:
  • Optional Features for ISDN Centrex
  • Centrex Virtual Network/Regional Centrex Virtual Network
How do I order?
To order, or for more information, call the Centrex Service Center at 800.321.2000 Monday through Friday 8 am to 5:30 pm Central.

Community forums

Have questions about your Business Phone service? Explore our community forums for answers.