Cable to Optical Network Terminal

I believe the inside connection from the ONT is just a cat5/6 connection (actually twisted pair will do).  The gateway end uses a RJ11 plug.  If there is a socked for the ONT connection in the wall and it is a RJ11 socket then you might get away with using a telephone cord.  Probably cat6 is better for fiber speeds.  Couplers exist for RJ11 to RJ45. 

Update:

Did I misinterpret what you want and you want to actually replace the line from the ONT to some other wall location and thus need to pull a longer line?  Again I believe it's a twisted pair but I wouldn't recommend phone line for an in-wall placement.  Probably want to actually use cat6.

All the pictures of ONTs that I've seen have RJ45 jacks for the Gigabit Ethernet connection.  Likewise, the proper jack on the Gateway is also RJ45.  RJ11 jacks are used for the DSL connection port and the voice port.

As this cable is being used as 10Base1000 (due to carrying the Gigabit Ethernet protocol), I would strongly suggest Cat5e or better twisted pair cabling.  If you actually have a wall plate with an RJ45 jack that you need to run a cable to from the ONT, then you should be able to purchase a standard Cat5e Ethernet patch cord.

Likewise, the proper jack on the Gateway is also RJ45.

@JefferMC

I thought the gateways used for fiber are NVG599 and 5268. For fiber does the connection from the ONT plug into one of the 4 yellow RJ45 ports?  If not the green broadband port is RJ11.

I'm looking for the cable that comes from the wall and into the ONT.  It is a very fine white cable with light streaming from the end into the ONT.  It is not like a phone jack or a connector into the router -- it looks more like the optical audio cable that runs between my sound bar and my TV.  All the ones I've seen online have two connectors, but I only need 1.

---

@skayg5 wrote:

I'm looking for the cable that comes from the wall and into the ONT.  It is a very fine white cable with light streaming from the end into the ONT.  It is not like a phone jack or a connector into the router -- it looks more like the optical audio cable that runs between my sound bar and my TV.  All the ones I've seen online have two connectors, but I only need 1.

---

The word "cable" does not include "fiber" which would apply to anything having light coming out of it.  If the optical fiber that is supposed to be feeding your ONT has pulled out of the ONT, you should call AT&T to come fix that, there is nothing about that you should be touching.  You may send a Private Message to @ATTU-verseCare or call AT&T Technical Support at 800-288-2020.

Yes, the Gateways used for fiber are the NVG599 and 5268ac.  You would not plug into one of the yellow LAN ports, but instead the Red port labeled ONT on both the NVG599 and 5268ac.

Hmm, an inch away and I didn't even notice that little sucker!   It just shows how we (or me) can view things with mental blinders on?  That, or it's just age!   Thanks for pointing it out.