I took an OBi110 and factory reset it then proceeded to upload the UK XML configuration file. Once complete I allowed the OBi110 to reboot and settle before unplugging it and taking it down stairs for testing.
Now I don't have any PSTN lines to test with as I'm 100% VoIP here but I do have an OBi202 in use so I used that as a PSTN replacement. My OBi202 has one of these connected to one of it's phone ports: http://www.surevoip.co.uk/store/surevoi ... 11-adaptor Anyway... I took the OBi110 supplied RJ11 to RJ11 and connected one end to the OBi110's Telco Line port and then connected one of these to the other end of the RJ11 cable: I then plugged the RJ11 cable coming from the OBi110 into the OBi202's BT adaptor, just like you I couldn't receive any incoming calls or make any outbound calls over the OBi110's PSTN line. There was an ever so slow blink of the green Telco Line light on the OBi110 maybe half a blink every second or so but no other activity! I removed this from the OBi110's RJ11 cable: I then removed this from the OBi202's phone port allowing me to connect the RJ11 coming from the OBi110's Telco Line port directly into the OBi202's phone port. Bypassing any BT/RJ11 adaptors: Connecting the RJ11 directly into the OBi202's phone port resolved the issue, inbound and outbound calls now work OK via the OBi110's PSTN line port!
I then took an old RJ11 to BT cable from an old BT corded phone I had laying around and connected it to the OBi110's Telco line port and connected the other end directly into this on the the OBi202's phone port: And the result was it worked!
It appears to be that the OBi110's supplied RJ11 cable will not work some or all of these: It appears to be related to this thread: WelshPaul @ OBI110 Need Help
Looks like you will either need to find an old cable that works or buy one from amazon.