Monday morning blues set in slightly late as Calcutta got into working-day gear, but once the business hours set in, calls not being completed and "network busy" messages became the norm till the evening peak hours.

The word from the two major operators was as contrary as the call conundrum. An Airtel spokesperson blamed it all on the "points of interconnect" between BSNL and the cellular operator.

"Because of the problems at BSNL's end, a channel that can support, say, 10 calls was bearing the burden of 100. As a result, 10 calls got through, while 90 were in queue and clogged the network," he explained.

The advice from Airtel: "If you are trying a number and don't get through, don't redial. Wait for a few minutes before trying again."

Hutch, however, said "there was no problem" on its network, and rubbished the technical claim of its rival.

"In case of local cell-to-cell calls, points of interconnect with BSNL do not come into play at all. Only in the case of calls going to another circle do they have to be routed through BSNL's trunk exchange," claimed a Hutch spokesperson.

With Calcutta playing host to over 13.8 lakh cell users and an almost equal number of fixed phones, essential services from hospitals to airports were hit hard on Monday.

If at Netaji Subhas Chandra Bose International Airport, both external and internal telephone services were affected, the public reservation system of the railways went off-track till 12.30 pm.