From Rcaman
LEC is Local Exchange Carrier. Could be AT&T or Verizon or South West Bell. Since you said you are on a farm, it's a very good bet you are served by a SLiC 96 or other form of high capacity line concentrator. The LEC uses these kinds of devices to put hundreds of lines and services on two pair of wires. This is commonly done in rural areas as the cost of installing fiber or more copper is prohibitive.
From what you are describing and now knowing you may be "out there" my opinion is that the service they are providing you is marginal at best. For the ESI remote phone to work consistently, you need at least a 512 Kb bandwidth service. That's not a "peak" bandwidth but a consistent bandwidth. Since the phone was working previously and just started failing after AT&T "upgraded" you, have AT&T go back in their records and find out what level of service they were providing you and ask them for the equal or better with Uverse. This may be something as simple as provisioning the AT&T router for more bandwidth for the ESI circuit.
Rcaman
