Introduction
For as long as Android and Apple phones have been on the market, IT administrators tasked with providing private cellular coverage know that out of the box, Android is a much more open than Apple in providing cellular metrics beyond the simple signal bars indicator.
Android phones, via the Google Play Store, can have downloaded on them various free (or relatively less costly than other more feature-filled) tools that can be used to survey private cellular networks including Ping Tools (including traceroute) and Aruba Tools (for iperf3) for networking, and for cellular metrics Cellinfo (for RSRP and PCI) and Network Signal Guru (free to try then $50 a month for mapping cellular coverage).
For iOS, while there are ping and traceroute tools in the Apple App Store, there are no 3rd party tools in the App Store for surveying cellular metrics such as RSRP or PCI. Apple has a publicly undocumented “Field Test Mode” that will let you view some current cellular metrics.
Field Test Mode for Apple iPhone devices
To enter Field Test Mode on an Apple iPhone, dial *3001#12345#*.
Anyone can write up a quick “do this” blog, but at Celona, we’re going to take it a bit further in the detail to help you get the most value from the Apple Field Test Mode.
Note that this Field Test Mode code must be entered on the iOS dialer and not via a saved contact. If attempted via contact, the Field Test Mode will not be engaged.
Field Test Mode for private cellular networks (including for a Celona private cellular) will show more detailed data for the cellular network that is currently in use.
When Celona is the only cellular network attached and showing bars (i.e. the public Mobile Network Operator (MNO) SIM e.g. AT&T is turned off), then the Field Test Mode will quickly show Band, Bandwidth, PCI, RSRP and SINR.
Similarly, when only an MNO SIM is enabled, cellular metrics for LTE and 5G can be seen for the public network, along with the other public bands that can be attached to.
what happens when both the MNO and Celona SIMs are enabled? As mentioned prior, the Field Test Mode will show data for both cells. However, only the currently active cell will get detailed and most updated data. Data for the cellular network that is selected in Settings > Cellular > Cellular Data, will get its data updated more frequently. As the data is not timestamped, you should consider RSRP and PCI data to be stale unless it has recently changed.
If you are looking for the most recent cellular data, ideally you should have only one cellular network enabled. If you must run with both MNO and Celona SIMs enabled, make sure to have Celona as the preferred network and log only the most recently updated data.
Field Test Mode for Apple iPad devices
The Apple iPad models with cellular capability do not have a dialer application. We found a set of instructions at forum.macrumors.com (search for “Here’s a way to access Field Test Mode on iPad Cellular”). In summary, the process involves downloading a shortcut and adding it to the Home Screen.
Field Test Mode on the Apple iPad takes a bit more to setup than on an Apple iPhone, but once it is done, it is much faster to invoke via an Apple Home Screen shortcut.
