A service provider node (101), and a method therein, for transmitting data packets relating to parts of a service to a communication device (102). The service provider node and the communication device are communicatively connected over a communications network (104) and comprised in a communications system (100). The method comprises receiving (205, 302) a signal (S1), which signal comprises an identifier of the communication device requesting a service, an identifier of the requested service, and an agreement comprising information about a previously agreed part of the service. The method comprises further agreeing (303) on an upcoming part of the service requested by the communication device, while transmitting (206, 304) data packets relating to the previously agreed part of the service to the communication device, wherein the data packets are transmitted in dependence of the received signal.