A method of upgrading software in network elements of a telecommunications network where operation of a plurality of network elements of a first type depends on operation of a network element of a second type. The method comprises receiving upgrade packages by the network element of the second type and at least part of the network elements of the first type. At least part of the network elements of the first type entering a waiting state and starting their upgrade when start of the upgrade of the network element of the second type is detected.