When an incoming call come from PSTN, it will be forwarded to one of your internal extensions, for example, extension 6001. If your Ext. 6001's voicemail is activated, please try to disable it and see what the result is.
If all the above trial is in vain, I suggest you to roll back to previous version like SVN432 or SVN437.
The default settings in Analog Trunks are for the USA. I think it is a bit different from European's requirement so that why you might need to fine tune for adapting itself to your own territory.
BTW, IP01 has an option in CID signalling for DTMF (Denmark, Sweden and Holland).
The problem arise after I switch to hkbn analog line, use a basic phone, there is a lof of a lot of echo. so I will call HKBN to see if the problem is cause by them.