Hi:
Thanks for the "noob warning". It's fine; we were all noobs once.
An OBiTALK device is not a free telephone gizmo. It is a device that needs to be set up with telephone service from a service provider. Most consumers buy them thinking Google Voice is a free telephone company. It's not. It is a call forwarding service.
I'm going to assume you want to use Google Voice; if not tell us what service provider you are using (e.g. Anveo, Callcentric,
voip.ms, Phonepower, etc.)
You need to a) get an inbound Google Voice telephone number, and b) "link" (add and verify) one or more forwarding destinations, from which you will make and receive calls. OBiTALK devices are simply one type of forwarding destination. You can also add up to six regular US land line or mobile numbers, and you can also make VoIP calls using Google Hangouts.
At minimum, after successfully obtain a Google Voice number and you set it up on your OBiTALK device, you need to go into Google Voice settings and create/save a voicemail PIN. You'll then call into your Google Voice number from your OBi-attached telephone, or one of your forwarding phone numbers, to hear your messages. You'll need to enter your PIN and # to access the menu.
Using a laptop/desktop computer's web browser, go here:
https://voice.google.com/settings This is where you will manage all of your Google Voice settings. Some settings have not yet migrated over from Google Voice's old settings page, and the voicemail PIN setting is one of them. To get there, click the three horizontal-bar "hamburger" menu icon in the upper left corner of the page, then scroll down and click "Legacy Google Voice". On the legacy site, click the gear icon in the upper right corner of the page and then click Settings. Now on the Settings page, click the "Voicemail & Text" tab. Finally, type in a PIN (I recommend using 8 digits, not 4) twice, then click the save button.
You can now call your GV number to hear voicemail. Note that you can only hear messages that are "new". Once you listen to a message, it won't be available again unless you save it as new.
The better way to manage voicemail and text messaging is from the Google Voice website or Android or iOS apps.