Incoming GV calls don’t ring my OBi if linked cell phone is in airplane mode

[MikeMan83]

Hi all. I searched the forums for this problem, but couldn't find an exact match...

My setup:
-Landline phone connected to OBi 200
-GV configured on OBi SP1
-Anveo e911 configured on OBi SP2
-"Cell Phone" set as a forwarding number in GV dashboard [see Figure 1]

The problem:
When my cell phone is turned off, all incoming GV calls go directly to the cell phone (AT&T) voicemail instead of ringing the OBi. For some reason, the cell phone has to be turned on in order for incoming calls to ring both the OBi and the linked cell phone. Everything used to work correctly with the cell off, so I am not sure what happened. Here are the basic troubleshooting steps I tried thus far:

-Factory reset OBi
-Removed and re-added OBi in GV dashboard and OBiTALK
-Removed and re-added "Cell Phone" in GV dashboard
-Confirmed that GV is set to ring OBi and "Cell Phone" before going to voicemail [see Figure 2]
-Confirmed that landline was set to go to voicemail after 4 rings
-Confirmed that issue does not occur when forwarding to "Cell Phone" is disabled in GV

I would greatly appreciate any help you can provide!

[Taoman]

When my cell phone is turned off, all incoming GV calls go directly to the cell phone (AT&T) voicemail instead of ringing the OBi. For some reason, the cell phone has to be turned on in order for incoming calls to ring both the OBi and the linked cell phone.

Set up conditional call forwarding on your cell phone and point it back at your GV number.

Under your cell phone in GV settings, click on "Activate Google voicemail on this phone" and follow the directions.

[MikeMan83]

Set up conditional call forwarding on your cell phone and point it back at your GV number.

Under your cell phone in GV settings, click on "Activate Google voicemail on this phone" and follow the directions.

My apologies - I should have clarified that I wish to retain use of the cell phone's AT&T voicemail service. Previously, when my cell was off or in airplane mode, all GV calls would keep ringing the OBi/landline and eventually be picked up by the landline's answering system, rather than going directly to AT&T vm