Hi Alexander,
a bit of a late response, but
On the similar venue, I'm thinking about delivering SMS to SMPP over unstable links (e.g. satellite), where the link may be inaccessible for non-negligible amounts of time. To make this usable, we need a queue in front of the SMPP interface.
I would appreciate if that could be handled outside osmo-nitb by something like a stand-alone SMPP caching proxy. This proxy would behave as an SMPP ESMSE, accept any MO-SMS from the NITB, cache it locally and postpone delivery to the real ESME. This way OsmoNITB doesn't have to add code specifically for that situation.