Like without network infrastructure?:) Then you are looking for satellite phones and similar (forbidden or highly controlled in many countries;) Definitely not BLE or sub-GHz ISM band low-power radios. Nordic are working on cellular (GSM/LTE) based low-power chip but no announcements about availability yet.
Like without network infrastructure?:) Then you are looking for satellite phones and similar (forbidden or highly controlled in many countries;) Definitely not BLE or sub-GHz ISM band low-power radios. Nordic are working on cellular (GSM/LTE) based low-power chip but no announcements about availability yet.
