How I can prevent my headset's microphone from picking up an echo?

For working remotely, I recently bought a Logitech H390 so that I can communicate with my coworkers remotely from my WinXP machine using software integrated with our company's phone system. Unfortunately my coworkers consistently complain of hearing an echo of their voice. After some experimentation, it turns out that muting the mic on the headset removes this echo, so its pretty clear that my headset's mic is picking up their voice and sending it back to them.

Someone suggested I search for other mics that might be on my system, maybe built-in to my laptop. I found one potential mic and disabled it in the device manager. This has had no effect.

I've tried modulating the gain on the mic, lowering it and this has a very small effect. Lowering the headset volume has a pretty big effect. Unfortunately when I'm participating in meetings and everyone's sitting around a speaker phone I need to up the volume to strain to hear what everyone is saying around the conference table.

I've looked on logitech's website to see if I'm missing any special drivers/software that I should be using. There are no downloads listed when I lookup my headset.

So I appear to be in a conundrum, I can raise the volume so I can hear but produce an echo, or I can lower the volume and not hear.

Is there any way I can cancel the echo from my headset's mic more effectively while being able to have the volume at a comfortable level? Should my softphone software be doing a better job at echo cancellation? Or is it my headset that stinks?

Since its for work its worth trying( buying?) a different mic . Better yet call a friend using the same mic with google voice . If the same echo occurs while using google voice then its the mic . If not your mic might just be incompatible with your companies software .