originator to terminator, and this results in people talking over each other. This can also result in many signaling timeouts as confirmation packets for certain events are expected to be received in certain time frames. Packet loss has a negative effect on any network, and in the IP network of a SP offering SIP trunks, the effect of excessive packet loss is that the voice quality is below acceptable levels and that call setup times can be long because of lost call setup packets. Finally, jitter, which is variabil- ity in delay, has a negative effect on the adaptive jitter buffers of endpoints in SIP trunk- ing solutions. Generally, endpoints adapt to a specific amount of delay by creating a packet buffer that is long enough to store packets for the expected largest delay (such as 30 ms dejitter buffer, or holding area for voice calls). However, if there is a sudden, large increase in delay in the work (that is, to 300 ms for example), the adaptive jitter buffer has to expand to accommodate this (as such, delaying all packets 300 ms before playing out). If there is a sudden decrease in delay, the adaptive jitter buffer has to contract to accommodate this (for example, back to 30 ms). This expansion and contraction of the dejitter buffer because of changes in delay of a net- work, known as jitter, has a negative effect on overall voice quality. 64 SIP Trunking The impacts of these network impairments are even larger when SIP trunks are used for video, which has less tolerance of bad-quality IP networks than voice networks. Another basic aspect of a high-quality IP network is security. Security implies that the basic network should not be full of bots, worms, or other infected devices that try to attack valid network traffic. A secure network also implies that there are not rogue ele- ments snooping on packets and that the traffic that flows across the network is from known sources and is valid. Generally, the Internet, which has thousands of infected enti- ties doing port scans and IP ping attacks, is not a secure