There have been a couple of times where customers have called my business after hours. They leave a voicemail but for some reason, the OOMA app on my iPhone will not notify me!
When I used to use RingCentral's app, I was notified immediately whenever someone left a voicemail either if I missed the call or it was after business hours.
I have gone through all of the settings on the iPhone and on OOMA webpage to see if I have mistakenly missed a check mark or a setting.
It seems that the OOMA iPhone app goes to sleep and will not wake up until you restart it.
Maybe it's just my phone.
OOMA Office User since 2015