Verify Permissions of your Number
The first thing you need to is to make sure that the number you are working on has the permission to receive and send SMS/MMS. You can do that by going to your Phone Numbers admin page (https://phone.smrt.studio/phoneNumbers) and checking the Capabilities of the numbers.
voice: the number can make and receive voice calls
sms: the number can make and receive SMS
mms: the number can make and receive MMS
Set up your SMS Flow
In order to receive SMS/MMS you need to make sure that the flow the number is assigned to has an SMS Flow active and that it is configured correctly.
In general, most people use the "Sms Inbox" applet which simply accepts the SMS/MMS and sends it to Podio into your Communications App.
You can chose to have the inbox set to:
User - in which case it will send to Podio and only show up in the web application/mobile inbox for the user selected.
Group - in which case it will send to Podio and show up in the web application/mobile inbox for all users who are in the selected group.
Read About Voice Call Flow Options: