Problems with analog trunk noise is legendary with IPO. It appears that in most cases the "echo" heard is actually delayed side tone since the IPO user hears the "echo" and not the person on the other end of the call.
There are many entries here at Tec-Tips and elsewhere that offers some remedies to this problem and the problem with noise. You can reduce the transmit gain on the analog trunk, turn off ACG on an IP phone, have the CO bring the trunks into specs, make sure your box is fully grounded, use you inductive amplifier to identify noise that can be induced on the trunks and some other items I am sure that I am forgetting(haven't had first cup of coffee yet)
If your IP Phone supports the firmware you can use the 2.6 IP Phone firmware. This firmware offers a few extra bullets for reducing "perceived echo" in regards to AGC and sidetone.
One case I have noticed recently is that the echo and noice I have heard is actually AGC run amuk. As the call progresses you can hear the microphone become more and more sensitive. You can start to hear the environment in an almost speakerphone fashion. I suppose this would be called perceived crosstalk since a user reports this as hearing other coworker conversations. As AGC runs wild and the microphone becomes more sensitive the mic overamplifies the noise along with everthing else and the call becomes noisy. And of course sidetone goes to hell in this condition. Sadly in this case a processor and VCM swap did not help. The CO did test all trunks, repaired two trunks and all tests were within the posted tight specs. We were left taking out the IP Phones and training the site on their new digital phones.
Good luck
