Unable to connect with ZTE AC2791 USB modem (19d2:fffe) - wvdial works fine

[Dan Williams]

On Wed, 2014-04-09 at 08:47 +0200, Aleksander Morgado wrote:
> On Tue, Apr 8, 2014 at 7:57 PM, Nilesh Trivedi <nilesh.tr at gmail.com> wrote:
> > ModemManager (version 0.6.0.0, Ubuntu 13.10) is unable to connect to
> > internet via ZTE AC2791 USB modem (USB id 19d2:fffe). The device is
> > modeswitched correctly, the menu item shows up correct in NM-applet but
> > after connecting, it immediately gets disconnected, the UI shows the entry
> > as "Label Empty" and cannot be connected again.
> >
> > Wvdial is able to provide a stable connection with the same device with
> > config parameters given as per this blog post:
> > http://www.anuragbhandari.com/2011/01/bsnl-evdo-in-linux-the-easy-way/
> >
> 
> We don't actively support MM 0.6 any more (> 1 year old), truth be
> told. MM 1.2 was released some months ago.
> 
> Anyway, can you try to get debug logs of both ModemManager and
> NetworkManager to see what could be happening? You can follow these
> steps:
> https://wiki.ubuntu.com/DebuggingModemmanager
> 
> If you're into it, maybe you could also try to gather debug logs with
> MM 1.0 to see if the issue also happens there. You could do so using
> e.g. a LiveCD of Fedora 20 or other distro which ships a more recent
> ModemManager. These would be the steps for MM 1.x and NM:
> http://www.freedesktop.org/wiki/Software/ModemManager/Debugging

Note that somebody from ZTE just posted kernel patches moving that USB
ID from zte_ev.c back to option for some reason.  There was no
information in the patch as to *why*, but I guess they have some reason.
I've tried to find these devices on eBay but nobody seems to sell the
ZTE USB CDMA ones.

Dan