​[fritz] Add roaming status and advanced LTE metrics for mobile routers (e.g., FRITZ!Box 6820)

[ctanno]

​The problem
Currently, the AVM FRITZ!Box Tools integration provides great sensors for connectivity and data usage. However, for LTE/5G routers like the FRITZ!Box 6820 LTE, knowing whether the router is currently roaming is crucial to avoid unexpected data charges. Furthermore, advanced mobile metrics (like current access technology or signal strength) are missing.
​Integration causing the issue
fritz
​Proposed implementation
I tested the TR-064 API of my FRITZ!Box 6820 LTE using fritzconnection. The router actively exposes the roaming status and a lot of other useful mobile metrics under the service X_AVM-DE_WANMobileConnection:1 using the GetInfoEx action.
​The most valuable additions for binary_sensor or sensor entities would be:
​NewRoaming (True/False)
​NewCurrentAccessTechnology (e.g., LTE)
​NewSignalRSRP0 (Signal strength)
​Here is the full raw output of the GetInfoEx call for reference. Since the integration would need to call this action for the roaming status anyway, maybe some of these other parameters could be exposed as sensors as well!

NewSerialNumber: XXXXXXXXXXXXXXX
NewEnableVoIPPDN: False
NewPPPUsername:
NewPPPUsernameVoIP:
NewSoftwareVersion: 03.01.41.16
NewUptime: 62930
NewPDN1_MTU: 0
NewPDN2_MTU: 0
NewIMSI: XXXXXXXXXXXXXXX
NewAPN_VoIP:
NewAPN: gprs.swisscom.ch
NewRoaming: True
NewCurrentAccessTechnology: LTE
NewSignalRSRP0: rx2=-98,main=-98,rx1=-99
NewSignalRSRP1:
NewCellList: 31primarylte23001T-Mobile Czech RepublicXXXX161105095-7-98XXXXX-XX

[mib1185]

• let's go ahead in [fritz] Add roaming status and advanced LTE metrics for mobile routers (e.g., FRITZ!Box 6820) #3406 as it is the better written request