You need to edit your MMS so you can use the service on Brightspot.
Go to Settings > cellular + SIM > SIM settings > edit MMS APN and input these values:
APN: multibrand
Username: <Leave blank>
Password: <Leave blank>
Authentication type: <Leave as is "PAP">
WAP gateway (URL): 216.155.165.050
WAP gateway port: 8080
MMSC (URL):
http://brtspt.mmsmvno.com/mms/wapenc
MMS port: <Leave blank>
Maximum MMS size: <Leave blank>
IP type: IPv4
If this does not work get back to us here or see the Brightspot people and don't forget where the settings are to show them.