On inbound calls the phone will only ring once the jump to the next step in the call flow whether it is voicemail or another extension. This issue only happens on Monday, by Tuesday it has resolved itself somehow. This is defiantly a pattern as this is the 3rd Monday this has happened on. All 3 customers are running on Linux Debian 9.
An oncologist is a type of doctor who deals with patients afflicted with one or various types of cancer. His/her work involves consultation, diagnosis, application of chemotherapy and coordinating with other doctors involved in treatment etc. This is how the phone greetings for oncologist should be like:

Phone call ring then voicemail sometimes and then goes right to voicemail no ring what does that mean phone off or ignoring call. I have metro pcs and my phone rings once then goes to voicemail when someone calls what could be the problem?
Voicemail access and the initial password should have been set by your carrier or service provider when your device was first activated. But keep in mind that some carriers don’t use passwords when it comes to voicemail. If you don’t know if this service is enabled or you forgot the password, you should check in with them first. If you see the contact list opening, tap on the phone dialer icon located in the bottom-right corner.Once you’re in keypad dialer, touch and hold on number 1 key. Now one of two things can happen. One, if you the service is enabled your phone will dial the voicemail number and prompt you to insert or create a new password. You might also be asked to record the greeting message at this stage. And two, in case your carrier didn’t configure this service when your device was first activated, you’ll be prompted with a message to insert your voicemail number. If the first scenario is the case, follow the instructions provided by your carrier to finish setting up your voicemail. In the event that you’re prompted to insert your voicemail number, tap on Add Number. If you don’t know your voicemail number, call your carrier and ask for it or search online for something like “voicemail number + *YourCarrierName* + *YourCountry*”. Now follow the instructions provided by your service provider to finish setting up your voicemail. Note: If you bought a used phone or you recently changed the service provider, chances are you have the wrong voicemail number set up. In cases like this, open up the App drawer and tap on Phone. From there, tap on More and select Settings. Once you’re in Settings, scroll all the way down to Voicemail settings and tap on the entry. This will open a pop-up in which you can change the voicemail number.