We attempt to estimate the Bit Error Rate BER) of a mixed network made of a classical and a Quantum-KeyDistribution-based (QKD) network, but including data traffic due to the Internet of Things. Firstly we carry out estimations of the probability of success call completion in the single case where a high user is under mobility and trying to do handover but also performing e-banking that is assumed that the end user needs reliability to carry out transactions without any risk to be hacked by eavesdroppers. It clearly needs to achieve handover using both IoT and quantum key distribution (QKD) networks resources. The simulation of BER have demanded to assume that the IoT handover and cell allocation follows a Shannon's entropy.