I had a factory OBI-EHS cable, which I used with a 2182, I needed a second for another 2182 (Amazon had them for $49!). Well I can't find it, they don't make it, and if I wanted it, I had to make it. So here is a diagram that worked for me with an Poly OBI2181, Poly SAVI 740, a Poly APS-11, and this cable. Take a RJ-45, I suggest a female keystone jack if you use the APS-11 since its a male RJ-45. On the other side you need a RJ-9 and an RJ-11 male to insert into the AUX and headset jack of the OBI2182 (other OBI phones should work as well if they worked with the OBI-EHS). I also suggest you get some shrink wrap. Hopefully the picture works, but here is the information in TEXT format. I doubt you need to do a T-568 wiring or any twists really, but since I used existing RJ-45 diagram, I used T-568B.
RJ-45
1-3 (RJ9)
2-2 (RJ9)
3--4 (RJ11)
4--3 (RJ11)
5--2 (RJ11)
6--1 (RJ11)
7-1 (RJ9)
8-4 (RJ9)