Different APNs for internet and MMS
MMS support was added in Spacebar some time ago. However, it doesn't work in all scenarios.
In the US configuration of mobile internet and MMS looks like this:
Internet configuration:
APN: fast.t-mobile.com
MMS configuration:
APN: fast.t-mobile.com (same)
MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc
And here is configuration of Polish t-mobile:
Internet configuration:
APN: internet
MMS configuration:
APN: mms
MMSC: http://mms/servlets/mms
Since in the US both configurations use the same APN, after adding it in the system settings and entering rest of MMS configuration in Spacebar, it is possible to use internet and download MMSs at the same time.
In Poland I was able to download MMSs when I set APN in settings to "mms", but I wasn't able to use internet then. When I changed APN in settings to "internet" I was able to browse the internet, but I couldn't download MMSs.
Spacebar in its configuration should allow APN different from that used for the internet and should work independently from the mobile internet.