Device, system, and method of Voice over Internet Protocol (VoIP) communications, and particularly of Real Time Protocol (RTP) communication. In order to improve quality-of-service or quality-of-experience for a group of VoIP calls that are served by a VoIP router, each VoIP transmitter implements and adds a pseudo-random waiting-period prior to transmitting each outgoing RTP packet, or otherwise re-orders or mixes or shuffles the order of channels of RTP packets that are buffered or queued for transmission. Accordingly, no particular VoIP channel suffers from repeated drops of its RTP packets at the VoIP router. Additionally, VoIP network analyzers operate to measure the overall VoIP network overuse, or the average RTP packet loss rate of multiple VoIP channels, based on measuring RTP packet loss rate of a single VoIP channel which enforces a random pre-transmission waiting-period.