Provided ATA and Soft/SIP phone on same network?

How easy is it to configure multiple devices (provided ATA along with a sip phone or softphone) to work together on the same nat-ed network? I await my adapter and sip credentials, and will need to connect the ata either behind my existing router/modem combo unit (Uverse) as a nat-ed or dmz-ed device, which I gather works OK...but question is can I additionallly use a byod device...that will allow ring, callout, answer successfully on same network (same number too)? If I have set udp range destined for the ata, how do I get this traffic alternatively to the sip phone at another ip?

Maybe I'm over-thinking this, as it appears others have it working?

I personally had issues. I had my ATA and softphone connected to the same network (behind the router). The router was set to forward UDP ports 5000-65000 to a static IP assigned to the ATA. I could dial out on the softphone ok, but was unable answer calls (rings but dead air when answered). The ATA was unaffected. If you are going to forward ports, you are likely to have problems. You might want to try without forwarding ports and see what happens.

FWIW, I do just what you are asking, and I do this all behind a NAT router, with no port forwarding. Granted, this is not VOIPo’s recommended configuration—and different routers behave differently—but I’m just chiming in to say this works very well for me, and I did little to nothing to get it that way.

Good luck.

So I got my GS 502 and hooked it to the Uverse gateway....works fine. As expected, a softphone on the same net rings, but answering call leads to a connection where the caller hears me, I hear nothing. Makes no difference whether I port forward udp ports to the GS or not. I gather this is really
an expected behavior.

Tech support said to "port forward the GS and put the SIP or softphone in router's "DMZ+"....but I think this would be afail as the way the 2wire RG works, DMZ device gets all ports, all traffic not specifically assigned to other ips........so UDP ports can still only go to one destination ip. What I'm investigating now is placing byod devices on another net in the home courtesy of additional public ips that I may assign to them....multiple DMZs kinda.
Trouble is, while I see ATT users saying this can be done and is available, their CS reps don't seem to know what I'm talking about.

I’d expect the multiple IP route to work flawlessly—as this really is the ideal scenario. That said though, if possible, you might want to replace the 2Wire router with something decent.

Follow up: I added a Panasonic SIP corded/cordless combo behind the router, right along and in the same
subnet, no port forwarding. This is using Uverse RG. BTW, the only way to "replace" the router with Uverse is to place a router in DMZ hooked to their RG device, as it contains the vdsl modem component. Anyway, happy to report all appears to work well. Still have plans to add a static ip maybe...will see if any issues crop up.

I can also say the Panasonic KX-TGP550 and 551 work quite well. Have it registered with VOIPo and CallCentric too.