sierra: read SID / NID from AT!STATUS response
Submitted by Aleksander Morgado
Assigned to ModemManager bug user
Originally reported at: https://bugzilla.gnome.org/show_bug.cgi?id=696591
The sierra plugin overrides the +CSS check for CDMA SID/NID because it can get that information from the AT!STATUS response, but currently it doesn't do that. We should enhance the !STATUS parsing code to read the SID and NID and (possibly the band) and use that to synthesize a reply for the get_cdma1x_serving_system() hook.
One thing to note is that many of the older Sierra cards don't have QCDM ports, so they don't benefit from the generic code's CDMA 1x Status handling, which is what normally reads the SID/NID for QCDM-capable devices.