Technical information

17
T1 Interface (RAS96xx/T1) FAQs
Q28. What is the best type of dial-in T1 line to get ?
A28. Any type of channelized T1 will work, but you probably should get an "Advanced
T1" line if you plan on using V.90 modems and want to provide connect speeds
above 33.6k.
An Advanced T1 line will almost always use Immediate Start or Wink Start as the
FXS signalling type. Most Ground Start or Loop Start circuits will not allow for
PCM (digital) connections. If you have obtained a Ground Start or Loop Start
circuit, make sure there aren't any digital-to-analog conversions between the T1
in the CommPlete and the telco's T1 switch.
Any digital-to-analog conversions between the CommPlete and telco switch will
eliminate any chance of getting PCM (connections above 33.6k) connections.
If you will be using the CommPlete for dial-in purposes only (such as an ISP site)
you will want to get a one-way trunk instead of a two-way trunk.
Troubleshooting FAQs
Q29. Why can’t anyone connect to my CommPlete V.90 modems
above 33.6Kbps?
A29. There are a few reasons this may happen. The most common reason is that the
user is calling in from a location that is routed through a telephone company
switch circuit that creates an extra digital-to-analog conversion.
Remote users are dialing with analog modems on an analog phone circuit. When
the call reaches the telco, it is translated to digital signals. If the signal gets re-
converted to analog at any point along the way, you cannot get a V.90 or K56flex
connection. Many residential areas are routed through more than one telco
switch, which will eliminate any chance of a V.90 or K56flex connection.
If a remote user is calling out through a PBX phone system (e.g., at work), they
cannot get a V.90 or K56flex connection. PBX phone systems create an extra
digital-to-analog conversion within the system.
The problem could lie at the CommPlete Server end of the phone circuit as well.
You need a Wink Start or Immediate Start circuit to get K56flex connections. If a
single user can get a V.90 or K56flex connection to the CommPlete, then the T1
connection between the CommPlete Server and the telco T1 switch is fine. If
there is a problem between the CommPlete Server and the T1 switch, no one
(not a single caller) would get a V.90 or K56flex connection.
Again, it is critical that there are no extra analog conversions along the entire
circuit. The basic circuit plan needs to look like this:
CommPlete <-digital-> T1 Switch <-digital-> Remote CO <-analog-> Caller