Right now my home telephone is connected to the phone jack on the wall, which the phone jack connected to my front door intercom(talking to the guest who pushes the ring bell). I also want to use this home telephone to connected with OBi202 device. So I can use it to make Google Voice calls as well.
How to realize both functions in my home telephone? Does it have anything to do with the 2 phone ports on the OBi device?
Thanks.
Do NOT connect your OBi to that jack for the doorphone. Doing so is likely to damage your OBi.
You would require additional hardware to have your phone do what you want. An ObiLINE (believed obsolete) might do it but some door phone systems do not use exactly the same standards as POTS lines.
Easiest option might be a 2-line phone.