Huawei E220: Sending SMS with blank SMSC fails with org.freedesktop.ModemManager1.Error.Message.SmscAddressUnknown

Submitted by Alastair Pharo

Assigned to ModemManager bug user

Link to original bug (#101761)

Description

I'm trying to use ModemManager to send SMS messages via a Huawei E220. This is working great, but at present it's necessary to specify the SMSC with each message in order to avoid an org.freedesktop.ModemManager1.Error.Message.SmscAddressUnknown error (AKA error 330).

I believe this is due to a quirk in the Huawei E220 which I have encountered previously in smslib 1, and is documented in 2 (search for “+CMS ERROR: 330”). Essentially, the modem seems to know the SMSC it should use, but needs to be explicitly reminded of it.

My patch to smslib which implements the fix mentioned in the blog post is 3. I'd like to submit a similar patch to ModemManager, however I'm not sure where in the codebase this should go. Perhaps in the "reset" function in plugins/huawei/mm-broadband-modem-huawei.c? Or is there a way that these AT-commands could be run before sending each SMS whenever no SMSC is explicitly specified?

Any direction on this would be appreciated. Thanks!

Version: 1.6