I have been a Ooma user for many years. I searched the forum for the answer to this question, and have not found where anyone else has asked this question for the Android Home Phone app.
I just finished speaking with a Ooma support tech about this question, and was told, "Yes, this is possible, but you will have to contact your phone provider for the answer to this question." When I contacted AT&T support about this request, I was told that it is not possible to do this unless I create a contact on my phone with the phone number(s) Ooma uses for call forwarding. I know that there is more than one phone number that the calls which are forwarded to cellphones come from because every time I get a forwarded call to my cellphone it seems to come from a different number other than the contact who is calling me.
So now, the question is, does anyone have a list of phone numbers I can add to a contact in my phone? I suspect the answer is, "Yes, there is a list, but... it's so many numbers that this solution is not feasible."
If that is indeed the answer, then please join me in adding a feature enhancement request to Ooma to add a customizable notification tone which can be used for the Android Home Phone app.