KARACHI, Jan 1: The PTCL is taking steps to upgrade the Karachi-IV Digital Telephone Exchange.

During the upgradation, the working of telephones starting with prefixes 690, 699, 696, 697 and 698 is likely to be interrupted on the midnight of Jan 5-6.

The subscribers have been advised to verify their code barring and call forwarding as these facilities will be deactivated due to the upgradation.—APP