Obi 200 problem

I have Obi 200 with Freephoneline. When somebody call me I usually hear 2 ring tones, pick up the phone and say 5 times "Hello"
The person who calling me hear 5 ring tones and only my last "Hello".

If somebody call me right away in few seconds / minutes everything works fine. Also my friend have Obi 100 with Freephoneline and the same configuration - I made installation for him ( different modem and internet provider ) and he do not experienced such problem.

What possibly I can change in configuration to resolve the problem or may be it is defective Obi device?