Organizations may employ private computer networks to enable customers to place a telephone call to customer service agents (CSAs). To maintain high customer service, it may desirable to expand the private computer network's ability to respond to customer calls on-demand. One or more requests for additional telephony resources may be submitted to a telephony resource allocation service in communication with a configurable network service. The telephony resource allocation service may determine telephony resources available for allocation to the private computer network and facilitate communication between the configurable network service and the private computer network. In this manner, additional computer private network extensions executing instances of call distribution services may also be generated and configured. Thus, the capacity of the private computer network to respond to customer calls may be expanded, while the additional private network extensions may manage distribution of calls to the CSAs transmitted over the allocated telephony resources.