Can anyone recommend a shared calendar service or app (Android accessible) that provides real-time notification alerts?
Real-time notification alerts would be for any new calendar entry as well as any change to an existing calendar entry (as opposed to reminder notification alerts). I tried Cozi & PlenoFamily apps and of course Google Calendar but none seem to have an adequate real-time notification alerts to those sharing a calendar (even though they say they do). For instance, a elderly person makes an appointment to see their cardiologist. Four family members & family friends sharing the elderly person's calendar instantly are alerted of the new appointment so they can coordinate among themselves as to who will also attend that appointment as a 2nd set of ears (as elderly person does not always hear everything the doctor says).
I believe "DropBox" has these features. I don't use it extensively, but it seems to be the most functional of all the Cloud Apps and the most reliable. They have a free version as well as a Pro Version for a fee.
Asana.com offers a great app for free - for a couple of projects; before requiring you to upgrade. Highly effective. We have used it our business, ZOX Pro Training, for ongoing communications and support. Mobile phone app is available for free too. Highly effective!
Take a look at Chaos Intellect (http://www.chaossoftware.com/in). I am not sure if it meets your requirements, but it is a very complete CRM and I find it very helpful. It has a function where you can schedule emails to go out at certain times, and it is very easy to set up this function. I use it on a laptop, but think it has mobile (Android )capability.
It is also very reasonably priced and I find custome service easy to use and knowledgeale.
I like gtask. It is the only one I have found with a widget that combines your to do list and your calendar into one. It syncs google calendars and windows calendars. It also has a windows, android, and apple app. I love it.
Office365 (O365), AKA SharePoint online, has standard capability to immediately email notify people about additions/changes/deletions, etc. from a shared calendar. And this works across Windows devices, Android, iOS, and even Blackberry ;)).
If you wanted text (SMS) that can be done via a simple workflow (which is configuration NOT code) or an add-in 3rd party product.
If you wanted telephony (as suggested by Matthew) that would be achievable through integration with Skype for Business, though that obviously requires higher cost subscriptions.
Having been forced to use Google for Business, I have to say I HATE it! Nowhere NEAR the flexibility of the MS product ecosphere that O365/Azure has become and continues to grow from.
John: Have you looked at calendly? They integrate with online calendars as well as Outlook. Look into their team edition.
Basically, you need something that will text, email, and maybe even automated-call people. No shared calendar solution is going to do what you need. Everything I can think of would require your clients to have accounts inside their system, and that immediately disqualifies them.
http://www.demandforce.com offers something like what you need, but I'm sure if you Google "customer appointment notification system" you'll come up with 10 possible vendors in a heartbeat. Or, call local dentists, optometrists, doctors or even restaurants that do text notifications for tables and ask what they've tried.
You could have a custom app built, but that would only reach a subset of your clients and anyplace that offers a business solution like mentioned above will likely already be able to private label an app for you or they will in the near future.