NEW DELHI : The telecom regulator has ruled that an incoming voice call on a mobile phone must ring for at least 30 seconds, resolving the deadlock that emerged when Reliance Jio and Bharti Airtel had locked horns over the matter.

Operators would have to maintain the time duration of alert for an incoming voice call, which is neither answered nor rejected by the called party, to 30 seconds for cellular mobile telephone services, the Telecom Regulatory Authority of India (Trai) said on Friday. “However, originating network may release an unanswered call after 90 seconds in case the call release message is not received from the terminating network."

While Bharti Airtel had said the ringing time be set at 45 seconds and argued that networks receiving the call must be allowed sufficient time, Jio had batted for a reduction to 20-25 seconds saying that it will save spectrum resources. Vodafone Idea wanted ringer time to be set at 30 seconds.

Trai had floated a consultation paper on the matter on 16 September.

Airtel, the country’s second-largest operator by revenue, had in September said it had cut the ringing time for outgoing calls to a rival network to 25 seconds from 45.

This was in retaliation to its bitter rival Jio’s move.

“Every second reduction on the ringing time saves spectrum resources for us," Mahipal Singh, associate vice-president of Jio, had said on 16 October in an open house held by the regulator. “94% calls on Jio’s network are answered within 25 seconds," he said, adding that the ringer time should be outside regulatory intervention.

Rival Airtel, on the other hand, said the timer should be set based on the preference of the network which is receiving the phone call.

“The time taken to terminate the call on a network should be uniform across networks. And the terminating or receiving network should be allowed sufficient time to answer the call. This should be 45 seconds," Ravi Gandhi, chief regulatory officer, Bharti Airtel, had then said.

If these ringing timers are set differently by different network operators, the chances of answering the call by user of one network would be different from the user of another network as one party would get more time to answer the call than the other party.

Also, every call that lands on a mobile network fetches it money. The interconnect usage charge or IUC is levied by mobile networks handling incoming calls from rival networks, and is a source of revenue for telcos such as Airtel and Vodafone Idea who enjoy more incoming traffic than outgoing.

At present, the IUC is at 6 paise a minute.

Interestingly, Jio, which reduced its outgoing call ringer time to 25 seconds, has more outgoing traffic than incoming. Jio’s outgoing traffic was 64% of its total voice traffic as of June end.

Airtel had alleged in September that with Jio reducing its outgoing call ringing time, the change in pattern results in a missed call, and forces the call receiver on the rival network to dial back and, hence, create incoming call traffic for Jio.

Jio, however, has argued that globally, most operators have an average ringing time of only 15-20 seconds, and 25 seconds ringing time on Jio network is in line with global practice.

The ringing time also impacts network efficiency. The maximum time allowed to answer the call takes on more importance as the alerting phase also engages scarce radio spectrum resources. Ringing for a long time, when a user is unlikely to accept the phone call, would led to non-optimal utilization of resources.

The reverse also has implications. Configuring duration of ringing time on lower side might save resources but may leaf to concerns over network performance, if duration is much lower than the typical time one takes to answer the call.