Dell 5540 (Ericsson F3607gw WWAN) problem - sim-missing

Question

Hello,
I'd like to use internal WWAN modem in my laptop (Dell E5440). Originally there was Sierra Wireless AirPrime (Dell 5570) which was not working at all on stock kernel. After some googling and tweaking kernel modules I got it to the point, where it was partially discovered, but ModemManager said "sim-missing". I left it in this state because I found nobody who ever got it working on Linux... but yesterday I got a chance to swap it with Dell 5540 modem. So i did.
And... it is not working ;-)
There is of course big step forward - as the modem is properly detected and so on, but... "sim-missing" keep appearing.
There is no entry of "WWAN" in NetworkManager.
SIM card is of course present. When I put this SIM card into Huaweii USB modem - it works - it shows in NetworkManager, accepts PIN and allows to connect to the network.
I have read https://wiki.archlinux.org/index.php/USB_3G_Modem and did as it was written.
I've found this thread https://bbs.archlinux.org/viewtopic.php?id=162295, but it's about version 0.7 of ModemManager and now we have version 1.2 so it is obsolete.
Does anybody has an idea what is wrong? What can I check?
root@pbr-laptok:/home/pabre# mmcli -L
Found 1 modems:
/org/freedesktop/ModemManager1/Modem/0 [Dell] D5540
root@pbr-laptok:/home/pabre# mmcli -m 0
/org/freedesktop/ModemManager1/Modem/0 (device id '8ccd82c9b505e0d67d0aeb17172869c8794fa61a')
Hardware | manufacturer: 'Dell'
| model: 'D5540'
| revision: 'R1K06'
| supported: 'gsm-umts'
| current: 'gsm-umts'
| equipment id: '353237030500996'
System | device: '/sys/devices/pci0000:00/0000:00:1d.0/usb1/1-1/1-1.8/1-1.8.3'
| drivers: 'cdc_acm, cdc_ether, cdc_wdm'
| plugin: 'Ericsson MBM'
| primary port: 'ttyACM0'
| ports: 'ttyACM0 (at), ttyACM1 (at), wwp0s29u1u8u3i6 (net), ttyACM2 (at)'
Numbers | own : 'unknown'
Status | lock: 'unknown'
| unlock retries: 'unknown'
| state: 'failed'
| failed reason: 'sim-missing'
| power state: 'low'
| access tech: 'unknown'
| signal quality: '0' (cached)
Modes | supported: 'allowed: any; preferred: none'
| current: 'allowed: any; preferred: none'
Bands | supported: 'unknown'
| current: 'unknown'
IP | supported: 'ipv4, ipv6'
SIM | path: 'none'
Bearers | paths: 'none'
root@pbr-laptok:/home/pabre# lsusb | grep Mobile
Bus 001 Device 006: ID 413c:8184 Dell Computer Corp. F3607gw v2 Mobile Broadband Module

Answer 1

I did, you linked to it already
I slightly modified modemmanager-git in the AUR and added some dependencies, the git version now works for me.