Add to ORKGApplication of IP telephony is still more and more popular. This technology is designed for large companies as well as for home or office use. If customer needs to use advanced features of the private branch exchanges, he had to purchase more expensive solutions than common equipment. These professional products may be replaced by open source solutions, which can fully replace them. Private branch exchange Asterisk is one example of these products. Bachelor’s thesis is focused on IP telephony, treats of basic principles and network protocols used by this service. This thesis then describes the public branch exchange Asterisk, its possibilities for use in call centers and administration of call queues using this PBX. After theoretical analys...