Hi,
I replied to your post here:
https://www.ukvoipforums.com/viewtopic.php?f=10&t=877&p=3934#p3934I am using normal RJ11 (UK) and some broadband filter connected to the another broadband filter
This is the cause of your issue!
A microfilter has two connections, one for broadband and one for the PSTN line - I take it you have connected the RJ11 > RJ11 cable running from the OBi110 into the port that is used for the BB and then plugged the BT plug that runs from that microfilter into the PSTN port on the second microfilter which in turn plugs into your BT master socket?