Comment 14 for bug 461096

I did some testing, and the problem seems to be with modem-manager and that the modem responds with a SID of 0, in IS-707-A format.

** (modem-manager:2779): DEBUG: (ttyUSB0): --> 'AT+CSS?<CR>'
** (modem-manager:2779): DEBUG: (ttyUSB0): <-- '<CR><LF>?, 0<CR><LF><CR><LF>OK<CR><LF>'

Modem-manager thinks SSD == 0 || SSD == 99999 means no service. According to some document i found, SSD=0 is actually a valid number.

> SID:
> 0-16383 The mobile station is registered with
> the system indicated.
> 99999 The mobile station is not registered.

I have no idea if this is correct or not, but i changed the test to check against 99999 only, and then it works for me.
If sid 0 is invalid in later specs; something more clever is needed...

I've attached a patch to allow sid 0.