Em7455 will not syncornize

[jyijyi]

are you using the latest FW?
https://source.sierrawireless.com/resources/airprime/minicard/74xx/em_mc74xx-approved-fw-packages/#sthash.2PNzT7s6.dpbs

How many devices are seeing this issue?

Also see related thread here:

Failed to connect RC76xx and AirVantage service

Hi @Vianney SIM is ok, I checked, I can oped PPP connection and send data, so the data channel is ok and the APN is correct. Today the device successfully connected with AVMS automatically after boot, but when I close session (AT+WDSS=1,0) and try to open it again, it wasn’t open, with no notification or errors +CREG: 1 +WDSI: 4 +WDSI: 6 +WDSI: 23,0 +WDSI: 4 +WDSI: 6 +WDSI: 23,1 at+wdss=1,0 OK +WDSI: 8 at+wdss=1,1 OK at+wdsg +WDSG: 0,3 +WDSG: 1,0 OK at+wdsi? +WDSI: 4479 at+…

you need to make sure no host platform is using the data connection