A method of testing a communication device or first network, comprising: at a remote test system: generating portions of test packets separated by time intervals between the test packets, encapsulating the portions of the test packets thereby forming encapsulated packets, and adding timing information to the encapsulated packets so as to preserve the portions of the test packets and information related to the time intervals; and transmitting the encapsulated packets over a second network to a local test device; at the local test device (502-504, 512): (i) receiving the encapsulated packets from the remote test system via the second network, (ii) extracting the timing information from the encapsulated packets, (iii) decapsulating the encapsulated packets so as to obtain portions of the test packets and the timing information, and (iv) forming replay packets, wherein the replay packets include the portions of the test packets; and, (v) transmitting the replay packets to the communication device or first network, wherein the replay packets are separated by the time intervals reproduced using the timing information, so as to imitate a stream of the test packets generated in step at the remote test system; wherein reproduction of the time intervals includes removal of jitter using a buffer. at a remote test system: generating portions of test packets separated by time intervals between the test packets, encapsulating the portions of the test packets thereby forming encapsulated packets, and adding timing information to the encapsulated packets so as to preserve the portions of the test packets and information related to the time intervals; and transmitting the encapsulated packets over a second network to a local test device; generating portions of test packets separated by time intervals between the test packets, encapsulating the portions of the test packets thereby forming encapsulated packets, and adding timing information to the encapsulated packets so as to preserve the portions of the test packets and information related to the time intervals; and transmitting the encapsulated packets over a second network to a local test device; at the local test device (502-504, 512): (i) receiving the encapsulated packets from the remote test system via the second network, (ii) extracting the timing information from the encapsulated packets, (iii) decapsulating the encapsulated packets so as to obtain portions of the test packets and the timing information, and (iv) forming replay packets, wherein the replay packets include the portions of the test packets; and, (v) transmitting the replay packets to the communication device or first network, wherein the replay packets are separated by the time intervals reproduced using the timing information, so as to imitate a stream of the test packets generated in step at the remote test system; wherein reproduction of the time intervals includes removal of jitter using a buffer. (i) receiving the encapsulated packets from the remote test system via the second network, (ii) extracting the timing information from the encapsulated packets, (iii) decapsulating the encapsulated packets so as to obtain portions of the test packets and the timing information, and (iv) forming replay packets, wherein the replay packets include the portions of the test packets; and, (v) transmitting the replay packets to the communication device or first network, wherein the replay packets are separated by the time intervals reproduced using the timing information, so as to imitate a stream of the test packets generated in step at the remote test system; wherein reproduction of the time intervals includes removal of jitter using a buffer.