Did you test your SIM in Windows?

Are you using LTE? I haven't successfully connected on 3G yet.

Here's what it looks like for me (phone numbers etc. redacted):

Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.2172] device (cdc-wdm0): Activation: starting connection 'Fido Default' (d99245e5-39f0-4639-91e2-5f22f68d864b)
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.2174] device (cdc-wdm0): state change: disconnected -> prepare (reason 'none') [30 40 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.2180] device (cdc-wdm0): state change: prepare -> need-auth (reason 'none') [40 60 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.3527] device (cdc-wdm0): state change: need-auth -> prepare (reason 'none') [60 40 0]
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect started...
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect state (4/8): Wait to get fully enabled
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect state (5/8): Register
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect state (6/8): Bearer
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect state (7/8): Connect
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: state changed (registered -> connecting)
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.3781] (cdc-wdm0): modem state changed, 'registered' --> 'connecting' (reason: user-requested)
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connecting -> connected)
Sep 06 13:08:39 t460s ModemManager[3309]: <info>  Simple connect state (8/8): All done
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6287] (cdc-wdm0): modem state changed, 'connecting' --> 'connected' (reason: user-requested)
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6308] device (cdc-wdm0): state change: prepare -> config (reason 'none') [40 50 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6311] device (cdc-wdm0): state change: config -> ip-config (reason 'none') [50 70 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6314] (cdc-wdm0): IPv4 static configuration:
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6314]   address 25.157.105.182/30
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6314]   gateway 25.157.105.181
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6314]   DNS 64.71.255.254
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6315]   DNS 64.71.255.253
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6377] device (cdc-wdm0): state change: ip-config -> ip-check (reason 'none') [70 80 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6399] device (cdc-wdm0): state change: ip-check -> secondaries (reason 'none') [80 90 0]
Sep 06 13:08:39 t460s NetworkManager[3225]: <info>  [1473181719.6452] device (cdc-wdm0): state change: secondaries -> activated (reason 'none') [90 100 0]

$ mmcli -L

Found 1 modems:
	/org/freedesktop/ModemManager1/Modem/0 [Sierra] MBIM [1199:9079]

$ mmcli -m 0

/org/freedesktop/ModemManager1/Modem/0 (device id 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX')
  -------------------------
  Hardware |   manufacturer: 'Sierra'
           |          model: 'MBIM [1199:9079]'
           |       revision: 'SWI9X30C_02.08.02.00'
           |      supported: 'gsm-umts, lte'
           |        current: 'gsm-umts, lte'
           |   equipment id: 'XXXXXXXXXXXXXXX'
  -------------------------
  System   |         device: '/sys/devices/pci0000:00/0000:00:14.0/usb1/1-2'
           |        drivers: 'cdc_mbim'
           |         plugin: 'Sierra'
           |   primary port: 'cdc-wdm0'
           |          ports: 'cdc-wdm0 (mbim), wwp0s20f0u2i12 (net)'
  -------------------------
  Numbers  |           own : '+1XXXXXXXXXX'
  -------------------------
  Status   |           lock: 'none'
           | unlock retries: 'sim-pin2 (5)'
           |          state: 'connected'
           |    power state: 'on'
           |    access tech: 'lte'
           | signal quality: '9' (cached)
  -------------------------
  Modes    |      supported: 'allowed: 3g, 4g; preferred: none'
           |        current: 'allowed: 3g, 4g; preferred: none'
  -------------------------
  Bands    |      supported: 'unknown'
           |        current: 'unknown'
  -------------------------
  IP       |      supported: 'ipv4, ipv6, ipv4v6'
  -------------------------
  3GPP     |           imei: 'XXXXXXXXXXXXXXX'
           |  enabled locks: 'fixed-dialing'
           |    operator id: '302720'
           |  operator name: 'Fido'
           |   subscription: 'unknown'
           |   registration: 'home'
  -------------------------
  SIM      |           path: '/org/freedesktop/ModemManager1/SIM/0'

  -------------------------
  Bearers  |          paths: '/org/freedesktop/ModemManager1/Bearer/0'