Any advice or ideas from those who have migrated all or most of voice to Teams? Our organization has a legacy Avaya phone system with traditional desk phones and assigned DIDs. We had strong adoption of MS Teams during Covid, with mobile phones, I don't think we need DIDs for new hires - but need routing for legacy, warehouses, EMS, and customer service.

Alex, we did an evaluation and determined Zoom was the best option for us, we to had an aging Avaya phone system with all the legacy one could want, in addition, we had added many other products to support a mobile user base.  Our user base is excited to see new technology that supports anywhere connectivity, while we still have a lot of folks that love desktop devices.  UCaaS give so much more flexibility, reduces overhead, and streamlines so much of the care and feeding of a phone system for us it was an overwhelming must-do.  If its teams or another solution is best for you, you should really look at moving off a legacy phone system.  Happy to talk more if you like

I would suggest looking at Voiso’s cloud call Center for your external facing teams.
We migrated a key satellite office from using onsite Avaya hardware to Voiso cloud, and we setup all the remote teams with it. All of the remote teams are very happy with it.
You get all the call recording, customised forwarding, optimised routing and troubleshooting that you will need. They are very responsive to support calls and flexible with their setup.