Cisco 7975 phone with Plantronics headset and a 7916 exp mod

[Michael Durham]

How can I get a 7975 phone working with a Plantronics headset (which is currently working fine) and I need to add a 7916 expansion module.  So far I cannot get all three to work together.  I can get the 7916 working with the 7975 and I can get the headset and the 7975 working.  

Any cabling suggestions?

[Roger Kallberg]

How are you connecting the peripherals to the phone? You should be connecting the headset to the headset port and the expansion module to the AUX port.

[Michael Durham]

I am connecting one cable to the headset jack (tiny 4 pin connector) and the other connector to the AUX )6 wire connector).  The problem is that the Sidecar also wants the AUX port.  The Sidecar does have a second AUX port and I tried connecting the Plantronics into that port (used for second Sidecar) but it does not fit, the cable is too short.  I made a short extension cable but the the headset still does not work.   Has anyone tried using a Y splitter in the AUX port and had any luck?  I really need both working for my job.

[Roger Kallberg]

Quite likely you’ll need to use another connector cable for your headset. If that’s not possible you’ll probably need to use another type of headset. What model of the Plantronics headset do you have?

[Nithin Eluvathingal]

Use a simple headset which you can connect to the head port. Use aux port for expansion. 
In this way you can make both working

[Roger Kallberg]

If you have one of these cables to connect your headset with the phone you will not be able to connect the expansion module as well as both use the AUX port.

https://www.founderstelecom.com/38350-12-apc-42-ehs-cable-headsets-cisco.html

You need to use a headset that connects with one of these cables to use the expansion module simultaneously.

https://www.founderstelecom.com/plantronics-u10-cord-cisco-26716-01.html

Like @Nithin Eluvathingal wrote you cannot use a EHS, Electronic Hook Switch control headset together with the expansion module.

[Nithin Eluvathingal]

If you are using EHS cable for plantations, you cant connect the expansion module as both use AUX port.

2.12.0.0

[Michael Durham · Accepted solution]

I finally figured a way to get everything to work together.  I bought a 6C6P all female RJ11/12 splitter and connected the cable that came with the 7916 to the 7975 phone and the other end to the 7916.  Then, I used a second 7916 cable and connected it from the second port of the 7916 to the splitter and then connected the HS50 Plantronics base to the splitter.  It will work though you may have to answer with the headset a few times to get it all synced.  YEA!!!