One of the most intricate sections of the 2101 is the PRI/T1 or TRUNK configuration. Despite a real effort made by the Telco companies concerning the Protocol standardization, there are still a lot of existing different protocols and options, depending also on the country.
The trunk configuration is made even more difficult when the unit is plugged in behind a PBX. If any problem occurs as a result of this action, neither the Telco nor Telos will be able to diagnose any issue related to the PBX. This is why Telos encourages communication with the Telco and the PBX manufacturer before installing the 2101.
See the Telos CSB on “Ordering ISDN PRI for use with the Telos 2101 Talkshow system” for the most current information on ordering PRI/T1 lines.
Trunk configuration
The whole trunk configuration is accessible by the Web browser.
- Connect to the Hub via the web browser.
- Select the LINE STATUS menu to access the card and port to configure.
Note: For a Dual PRI/T1 card Port 0 or A is the BOTTOM port, Port 1 or B is the TOP port. Dual port PRI cards rely on deriving the master clock from the line plugged into Port 0, bottom port. A single PRI line connected to the Top port only may have erratic behavior with the 2101 (such as dropped audio, dropped calls, etc.) or may not initialize at all.
Here is the main information to obtain from the Telco:
- Circuit type: PRI(Primary Rate ISDN) or RBS (Robbed Bit Signaling) used by T1
- Switch type
- Variant type
- Line code
The Switch type and the Variant type define the Protocol type.
The Framing mode is related to the circuit type:
- FrmESF – Extended Super Frame (ESF): usually for PRI or T1 in the USA & Canada
- FrmSF – Superframe: not for PRI, can be used for Channelized T1 if ESF not available
The Line length represents the number of feet of cable between the CSU (Channel Service Unit) and the 2101 Hub.
The Protocol type can be selected from some presets included in the software or a custom protocol can be created, in case the option you need is not available. Press ‘Properties’ in order to create a custom type. Two options can be changed:
- Switch type
- Variant type
NOTE: Difference between PRI and “Channelized T1”
With the PRI, a hunt group can be created (several channels using the same phone number) whereas the Channelized T1 has to have one phone number per channel. Thus, the Telco has to create hunt groups. T1 is generally configured as a channel-based hunt group (“Channelized T1” or “Digital Trunking”).
Telos recommends using PRI (Primary Rate ISDN) for its flexibility purposes. In this case the 2101 Hub can create the hunt groups as the customer needs them.
The only T1 type of line that Telos recommends is the “E&M Wink Start” line, configured as a “Two-way DID.” This works quite similarly to a PRI line. Note that with this line the T1 must be Dial Pulse signaling. (More details further in this section)
IMPORTANT- Any time you make a change to the port configuration you must RESTART the 2101 application. The PRI cards will not initialize to the new setting until you do this step. Restart the 2101 application from the Reboot option in the Software Update page.
NetAccess board type
Two different NetAccess boards are available with the 2101:
- PRI/T1: for USA
- PRI/E1: for Europe
Depending on the board, the available options will switch automatically in the configuration menu (framing mode, Line code).
Network Channel Terminating Equipment or CSU
The N.C.T.E. or CSU (Channel Service Unit) is a device located between the Telco trunk and the 2101. Its main use is to provide a higher level of electrical protection against storms or lightning. It is also pretty useful to the user to track any loss of signal coming from the Telco or from the 2101.
Outside the USA and Canada, the NTCE is generally the responsibility of the Telco.
Inside the USA, it is the customer’s responsibility to supply this device.
We generally recommend to the customer the following models for T1/PRI in the USA:
- ADTRAN model T1 CSU Ace (part # 1203022L1)
- ADTRAN model T1 ESF CSU Ace (part #1203025L1)
- ADTRAN model T1 ESF CSU Ace (part # 1204025L1)
There is typically no need to program these devices. They are like “plug and play” type equipment.
Configure phone lines
All the phone numbers available on the incoming service have to be entered here. Only program the numbers as sent by the Telco provider (ie. If the CO sends you 4 digits you program the 2101 with 4 digits.)
If you are using a PRI line that has no trunk groups and all channels are 2 way (inbound and outbound) you can leave the Channel field blank. This field is related to outbound calls. If you enter in the wrong channel numbers or range of numbers you may restrict the line appearances on the DD’s as well as this is used to calculate channel availability. Careful with this option.
(If you are using a channelized T1 you must specify which channel of the T1 each telephone number is associated.)
If your PRI line has trunk groups OR has specific channels assigned for outbound calls OR is provisioned with LESS than the 23 channel capability you can specify a range of channels that the 2101 must use for outbound calls for that phone number* (ie. 1-6 entered in the Channel field next to a trunk number allows that phone number to make outbound calls on channels 1-6 only). If you are using PRI, or a T1 protocol that uses Direct Inward Dialing/ANI (DID), you should just enter each of your DID numbers associated with the digital telephone circuit connected to that port. If your DID numbers are in a consecutive range you can specify a range of numbers in the Phone Number field separated by a hyphen.
IMPORTANT- Any additions or deletions of phone/DID numbers in this section requires the 2101 application to restart for these changes to take affect.
Upon restart of the 2101 application monitor the Status page of the Ports to see if the changes you made are correct and the PRI/T1 line properly initializes. If it does not go to Part-6 for troubleshooting tips.
Interfacing to a Business PBX
When interconnecting a PBX to the 2101 there are a couple of things to consider. First, you shouldn’t need a CSU between the two systems since most PBXs use the same interface card in their application for connecting to the Telco line. The PBX will act as the CSU. For connecting to the PBX you may need a T-1 crossover cable. Verify with the PBX manufacturer the pin out of the RJ45 connector of their card.
Second, the 2101 can only be a SLAVE to the PBX. The 2101 cannot be the MASTER clock to any interconnect to the PBX. The 2101 is also a slave in terms of the ISDN signaling to “Layer 2” and “Layer 3” messaging. If the PBX cannot be the master to the line the interconnect will not work.
When recommendations for configuration of the PBX, there are none. We do not have specifics on how to properly program every PBX in the world. The only recommendation we can offer is that the PBX must be able to emulate a line as if it were “generated by a Telco Provider” exactly. Often this is referred to as “LT” or Line Termination. The guidelines for the line parameters are in the PRI ordering form that we offer to the customers to send to their service provider. If the PBX cannot generate the same type of PRI/T1 lines we expect then the chances of the two systems ever passing calls is very low to never. We never make any guarantees that this type of setup will work. The responsibility is on the customer for proper configuration of their PBX.
If the customer wants to do this we highly recommend that the PBX generate a standard PRI line, nothing fancy, no extra messaging or features included, and to make it appear that it is being emulated from a 5ESS or DMS100 type switch. Standard protocols are preferred (NAT I-1, AT&T Custom, etc). The PBX MUST be the master clock. The 2101 cannot be the master.
For T-1 line, we would recommend E&M Wink Start (note: We test the 2101 systems in production with our Mitel PBX using SF T-1 RBS E&M Wink Start) This mode can still do DID numbers and the 2101 can still create hunt groups with the numbers. Important that the PBX only pass and accept DIAL PULSE signaling. The PRI/T1(E1) card can only do this type of signaling when sending or receiving calls. Once the call is established and the audio channel has been opened DTMF then can pass accordingly (such as if you called your VM and needed to access your messages from a touch tone phone).
A Channelize T-1 may work as well but the PBX would have to create any required hunt groups if needed. The 2101 system cannot do this for their PBX.
Programming the phone numbers and channels follows all the standard rules.
Channel Numbers
A note about Channel Numbers in the Trunk Config page. This field really relates to forcing specific phone numbers to use specific channels for OUTBOUND CALLS.
For a PRI that is untrunked, all channels may be two way, allowing both inbound and outbound calls. When you program your phone numbers you leave the channel field BLANK to allow the system to let any phone number to use any channel for an outbound call.
However if the PRI is set up that all channels have INBOUND call ability but only channels 1 thru 10 have OUTBOUND capability then when programming the phone numbers you should specify the channel fields 1-10 for all numbers required for outbound calls to force the 2101 system to keep call attempts limited to this range. This example the system will only allow a max of 10 outbound calls.
If the PRI is set up with Trunk Groups then you may want to restrict those specific phone numbers associated with each trunk group to REMAIN within their grouping for outbound calls. OR the Trunk Groups may have been set up with only one of the groups allowing outbound calls. For example, say group A on channels 1-5 allows outbound calls. Then any (or all) numbers used for outbound calls should be assigned to the channels 1-5. You could then force those phone numbers that are not required to call out to the other inbound only channels so they cannot call out (6-23). You get a dial tone but you wouldn’t get out of the 2101 for any call
Also be aware that if you restrict a DID number to a specific range of channels you should NOT program a show with more appearances of that DID number than channels associated with it. Say you have phone number 1001 on a trunk group assigned to channels 1-5 but you have a show with 7 appearances of 1001. You should get only 5 dots to populate on the DD’s.
But if your show has 5 appearances of 1001 and your system handles 5 calls to any other DID associated to the same range of channels you may see small “x”s appear on the DID for 1001. Though the “x” symbol means that the line is in use in another studio, on the 2101 it can also mean there are no more available channels for that line appearance to use.
Also regarding channels, the Telco tends to send calls in a particular order of the channeling. Most telco providers do a “Bottom-Up” call ordering for inbound calling where all PBX outbound calls do a “Top-Down” call ordering. (TOP channel is 23. Bottom channel is 1) The reasoning this is opposite is to prevent GLARE, the instance of when an inbound call hits an outbound call on the same channel. This is undesirable. There is an option within the System options to change the 2101 systems outbound ordering should the Telco’s ordering be different.
There have been scenarios where the telco provider has sent calls in a Circular order, starting on channel 1 then continuing up thru 23 then back to 1. This is NOT desirable and has the potential to cause glare problems. If you suspect this is happening with the calls then logging of the hub’s inbound calls will be required to verify.