We currently use SMS for our communications to end users, but that’s to a limited audience, and ITSM portal status pages. Not everyone gets the SMS and sometimes portal is not always easily accessible. We don’t have a dedicated comms team to respond to what could be lots of questions. How should we address this? 

If you are looking for systems than can do mass messages check out https://buildings.honeywell.com/us/en/solutions/safety/communications-notifications/instant-alert-plus

Our grammar schools used it as did our local city for public notification (potentially 50k people but don’t know how many signed up)

I worked for Honeywell so consider that as you evaluate

Over the years, we've experienced with different mechanisms to broadcast communication to end users.   The context was about system issues, downtime, etc.   How could we notify our 10,000+ branch employees of an incident.

At first, email sent to a group of 'special agent' within each branch was used.  Works ok but they are not always in front of their mailbox.

Then, a Portal that displays 'health status' or important message.  But sometimes, not always available (in case of a network problem) and employees don't refresh the page or visit it continuously.

We also tried sending SMS to a group of 'special agent' within each branch.   Quite effective.

Finally, we developped a mobile application.  The application gathers details from our incident management systems (HPSM and Service Now).   The application will send notification.  Employees can install it using the enterprise MDM portal (in-tune).

It's probably the most effective mechanism.  It's used for both branch employees and managers here, at the HQ.   

Steve