I have an Obi110 with pstn and gv on sp1. The setup is the standard setup that is created through the website. Everything works great except if the pstn is off hook, a person calling the pstn line gets a ring tone rather then a busy signal. The pstn line is simple measured service without voicemail or call waiting. I unchecked both boxes for CallWaitingEnable, saved and rebooted directly from the web interface but a call will still get a ring tone when they should get a busy signal.
To make sure there wasn't something wrong with the telephone line, I directly connected an off hook phone to the pstn line. A busy signal was generated for an incoming call.
How do I get the Obi to generate a busy signal?
You can solve the problem by hitting # immediately when you take the phone off hook. That immediately connects the phone directly to the pstn line and your dialing then goes directly to the phone company. Otherwise the pstn line isn't off hook until you finish dialing and in that case OBi then takes the line off hook to dial.
When someone calls a PSTN number they get the busy indication from the phone company because the line is off-hook unless you have call waiting from the phone company. The busy doesn't come from the OBi.
If you wish to handle an incoming call on the pstn line when you are talking on a voip call then you will need configure to forward the call to a voicemail on no answer or have an external answering machine pickup the call.