Monitoring Internet connection quality for cellular data connection

[timeshifter]

Have a client that has a 2 person office (soon to be 3 person) that is located in a rural area and can't get a good land line Internet from the cable company or phone company. They've been doing fine for years with a Cradlepoint device and an AT&T account getting their Internet via cellular. Well, fine is been passable but now we're needing to start using VoIP, etc.

We have a VoIP phone system in place and the provider has a monitor box (Microtik router, passthrough). They tell me that they can see times where the connection struggles, pings instead of being around 60ms will spike to 100ms or as much as 140ms at various times throughout the day. I can't access their box to see what's happening.

So, I'd like to get something in place. That way as I make changes and try different things I can see if it's helping.

I was pretty excited to find this

monitor-io - Troubleshoot and monitor your internet connections

Want to monitor the health of your home network? Want to see how your Internet service provider is performing? Want to see who is on your home network? Want to remotely monitor your smart IoT home network? Want to monitor 24 hrs of the day?

www.monitor-io.com

Looks perfect, except they're not selling them "Due to supply issues we are currently not shipping monitor-io products.
Our sincere apologies."

So I know there's Ping Plotter, have very limited experience with that, but I could certainly drop off a PC with it running and see what it does. I also use SyncroMSP, don't know if they have anything that will do the job.

Any suggestions?