sundance-communications.com/forum Forums Other TDM Phone Systems Vertical Telephones & Systems MBX/SBX phone outer pair (orange pair)

I just don't understand why the SBX phones that hook up to the MBX have to be wired on the orange pair. It just doesn't make any sense. Talk about a wiring cross connect conversion nightmares when only 1 pair was cross connected to the center pair on the old system.

Is anyone aware of a dongle device that can plug in at the phone that will bring the center pair to the outside pair? RJ14 - pins 2&3 to 1&4? So I would still have the signal coming in on the center pair through the line cord into the dongle that converts it at the phone to the straddling outside pair?

The only 'off the shelf' solution that I can think of is an RJ14 splitter, a 4/C modular line cord coupler and a short line cord.

Plug the phone's cord into the coupler.

Plug the RJ14 splitter into the coupler.

Plug the line cord into the splitters jack for line 2.

Plug the other end of the line cord into the jack.

i feel your pain. they had to do it that way on MBX because the sbx phones are designed that way. this happens when you do not have control over your manufacturing. It makes no sense in USA maybe it does it Korea. Just have to deal with it

Actually, when you think about it, it makes perfect sense. Since the SBX station ports in the main cabinet or on a 3x8 expansion card are hybrid (analog OR digital), depending upon which type of phone is connected, they had to do it this way. Once the port 'sees' a digital station connected, then it disables the matching analog port which resides on the first pair.

Analog ports aren't intelligent, so that was the only way to offer such flexibility. You have to admit that it is nice to have any mix of analog and digital station equipment on the system.

Panasonic has been doing it this way for decades. Their digital phones (72XX, 74XX, etc.) all use only the second pair to operate. It is just the lesser of two evils.

I see what you mean Ed. It is nice to have the abilty to do single line sets sometimes. But it is a pain to do a switch over on systems where the previous installer only did the blue pair. On our old systems we always terminated 2 pair even on the 1 pair systems. I guess there is no perfect anwswer

Thanks for the help. I know we could have gotten the MBX phones for 2-3 times the price for the same functionality. Oh well. It's working but not as eloquently as has hoped.

You don't have to always worry about the wiring to pins four and five...when using SBX phones with and SBX or MBX just cut one end off the line cord and retermintate the red/green wires to pins 3 and 6...it isn't that hard to do.