I own and operate a small MSP. I currently use 3CX for both my business and my customers.
I’m exploring FreePBX as an alternative.
I’m curious how the UI/softphones work with regards to the SMS. For example, in 3CX you can send/receive text/MMS either on the Windows/Mac/Browser Softphone, and on iOS/Android softphones.
FreePBX is just a frontend for Asterisk and Asterisk supports SMS. As for the softphones support that really depends on the softphone. In general the short answer is yes.