Campus Telephone system changes and modems

Over the next 18 months UO Telecom Services will be upgrading the hardware that connects the campus telephone system cabinets together.  These upgrades have the potential to adversely affect some modem connections to and from 346-xxxx phone lines.  We're told by Avaya (our telephone system vendor) that V.32 (9600 baud) and newer modems will work, but perhaps at somewhat slower speeds.  300, 1200, 2400 and 4800 baud modems are likely not to work once we finish our upgrades.  Very old fax machines (pre-1991) may also have problems.  We've done some rather extensive testing with a variety of fax machines -- they all talked to each other fine, albeit somewhat slower.

Note that the campus modem pool that Network Services runs will not be affected by these changes.

We've set up one phone system cabinet in a configuration that's very close to what we'll be rolling out system wide.  Please let me know if you have older modems or fax machines you would like to work with us to test in this new environment.

For those of you interested in the details:
The traditional time division multiplexed equipment we're currently using to connect our phone system cabinets will no longer be supported by Avaya past June of 2009 and hasn't been manufactured for a few years now.  The replacement involves connecting our 13 cabinets together with Voice over IP (VoIP) hardware.  A private Ethernet network will be built to carry IP traffic between the phone system cabinets.    While these changes will be transparent for users placing voice calls, the encoding from time division multiplexed (TDM) to IP and back will introduce some distortion that might affect modem and fax traffic.  Unfortunately, the digital signal processing games that are played to make voice calls sound better over an IP network tend to make things worse for modem calls.  (On a positive note, the new configuration will make it easier for us to add redundancy to the phone system, so that a failure at one site doesn't affect the entire system.  We expect to work on this aspect once the TDM to IP upgrade is complete).

Looking ahead, as more entities throughout the public telephone system deploy VoIP (and there are multiple TDM to VoIP conversions by different carriers for a single call), modem to modem calls (including faxes) are likely to become more problematic.

Please let me know if you have questions or concerns regarding these issues.

Eric Fullar
UO Telecom Services
346-1015