In an emergency measure in view of the restrictions around coronavirus, telecom companies are seeking to unlock intra-circle roaming between each other that would enable customers of one operator to latch on to the network of the other in case of no or poor signal.

from Times of India https://timesofindia.indiatimes.com/business/india-business/weak-signal-you-may-get-connected-to-another-telco/articleshow/74802116.cms