sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Help with 91B connecting block

I have a 1A2 system in my home consisting of a 551C KSU along with a number of 2565 phones with 4A speakerphones. I thought I would like a simple single line phone to have near my sofa so I bought four 91B connecting blocks, 2 of which had a 652C jack wired into the block and 2 had the jack integrated into the block. When I hook up the 25-pair cable and the single line phone there is nothing in the single-line phone although the 2565 works fine. Any ideas? Or is the 91B not made for this purpose. If not, what is the jack on the board made for?

Hi, I believe the 91A and 91B connecting blocks were used by the ComKey 416 (4A communication system) to supply the T&R to the Primary set (2 CO lines per jack). The connecting blocks are not compatible with 1A2 systems for 4A speakerphones. Check out the ComKey BSP 518-450-106. There are other connecting blocks, but I don't recall any that would bring out the T&R and A Lead pairs.

Remember, you need 2 pairs to your single line set, the T&R and A Lead. The A lead pair will cause the KTU to show the line in use, and light the lamps on any other phones. Without this, if you hangup a keyset that was on the line, the line will go on hold when the single line set picks up IF you don't have A lead control (if the single line set was pick-upped while the keyset was off-hook), or if the keyset puts the line on hold and then is picked up by the single line set, the Hold will not release and there will be a poor voice connection.

There are several methods to do what you want, some more elegant than others! Here is one way: 1. Your single line set has to modified to provide A Lead control as the first step in any method*. 2. Then I would connect the 2 pairs from the single line set to a modified amphenol plug (there are screw terminals for the 1st 2 pairs corresponding to T&R & A-Lead). 3. I would get a CPC (Connector-Plug-Connector) adapter and plug your nearby keyset in one of the connectors, the single line set in the other connector and the cable from the KS into the Plug. Then, when you pickup the single line phone, the corresponding lamp lights on all keysets; or if any keyset places the line on Hold, then picking up the single line set removes the Hold and the lamp is lit steady on all keysets. Hope this helps.

(*Others on this forum posted the conversion steps or alternate using a line sensing relay)

Here is the BSP for the ComKey that has the 91A and 91B connecting block: BPS 518-450-106

625C I assume?

Thanks jb for your response. I should add that my POTS lines were in my house long before the 1A2 system was added so I have multiple single and 2-line phones already being used in the house and none of them have the A-lead control functional. I already had a 2-line phone in the room that I wanted to put the single line phone but the wires were taped to the floor and hid under a rug. I had hoped to eliminate all that when I ran the new 25-pair cable to the desired location. I thought it seemed so easy to just put that 92B connector between the two 25-pair cables and pull off a tip and ring pair.

Bill, what you really need for this application is a 149A or B adapter. Those should be easy to find, in fact I believe that Suttle still makes them. It has a male/female 25 pair in/out setup, but also has screw terminals available for several pairs in the cable, including A1. It's true, the 91 type adapters just sent tip/ring in from the modular jack to pairs 24 and 25 on ComKey 416 systems only. Unfortunately, they only send this tip/ring IN to the station set, so unless you want to go inside of your 2565 sets and hack those pairs around, those adapters won't be of any use for your application.

Thanks for your reply EV. I do have some 149B adaptors but another telephone person [not on this forum] told me that there was no way I could pull tip and ring pair off the cable with a 149 connector block. He said I could pull about anything else off the cable but tip and ring. Is that true? I thought the #1 and 26 would be the first pair tip and ring. As I recall, there was no 1 and 26 on the 149B but maybe it was labeled differently.

Take a look at the Allen Tel AT153AM series for connectivity (first column, second row) on Product Overview.

Thanks, I have seen something similar to this made by Radio Shack [are they still in business?] where you insert this between the male and female plug and you can get 3 lines off of it. Your device though just connects to the female end of the 25-pair cable and that end is now essentially terminated, so I would have to run another 25-pair or use a bridging adapter. Can the 149B be used to pull off a tip and ring pair or not?

Possibly...

25 pr to 149B to Modular Jack using the T1, R1 for CO Line and T2, R2 for A/A1 of 149B

or

25 pr to AT153-01 [or equivalent] (T/R on 1, 26 and A/A1 on 2, 27) {cleaner install}

Correct, but there's access to a slew of yellow and violet pairs there. You'd just send your tip/ring and A/A1 in on unused yellow pairs from the KSU, for example yellow/blue for tip/ring and yellow/brown for A/A1. The 149 does have an A1 terminal, so even half of a pair could be used for the SLT's A lead.