Based on reports of the UIDAI's now-decommissioned toll-free number suddenly appearing in users' phonebooks even on devices with no Internet connection and even some with no SIM card inserted, Gadgets 360 staff set to checking a number of smartphone units in our possession. We set up a Huawei P20 Pro (Review) which had previously been reset to its factory condition, and found that the UIDAI toll-free number as well as a "Distress Number" entry, under which the national emergency hotline 112, had been saved.

Update: Google Takes the Blame for UIDAI Number Showing Up in People's Phonebooks

We then set up a Huawei Nova 3 (Review) and noted that the numbers weren't present, but they popped up a moment later. This unit also had no SIM card and we didn't allow the phone to connect to Wi-Fi during the setup process. Interestingly, we then repeated the factory reset process on both phones and found that while the two numbers did not pop up in the P20 Pro's phonebook the second time, they did the third time. They were also ready and waiting for us on the Nova 3.

The third unit we checked was a OnePlus 6 (Review), which had been lying idle with a Wi-Fi connection and had not freshly reformatted. Both numbers were present in the address book. Post a reformat, they were still there. The same was true when we went through the setup process on a OnePlus 5T (Review) that had previously been factory reset.

We did not find either number on our Asus ZenFone 5Z (Review), Samsung Galaxy J8 (Review), or Infinix Hot 6 Pro (Review) units we tested for at least 15 minutes after setting them all up. The next phone we grabbed was a Xiaomi Redmi Note 5 (Review), and both numbers were present after a fresh initialisation.

In all cases, we went through the setup process with Wi-Fi disabled and no SIM cards inserted. We left all settings at their defaults and skipped all optional steps. We did not sign in with a Google account or provide any form of personal identification.

We've reached out to OnePlus, Huawei, Xiaomi, and other OEMs for comments and will update this story as and when we hear back from them.