Originally Posted by jb66
Most likely would be the phone.
However possible causes include:
-Faulty extension wiring in the house
-Another phone off the hook or faulty on the line
-Certain fault conditions on the line such as a battery contact
-Virgin Media equipment e-side or beyond
What the customer perceives to be an echo could easily be the sound of another phone off the hook or a fault condition creating those circumstances.
Either way my previous advice needs to be followed for the customer to rule out:
-The person they are calling
Everything else is VM's problem so at that point they should report it.