v2 session target ipv4 : 10.10.1.1 dtmf-relay rtp-nte ip qos dscp ef media ip qos dscp CS4 signaling no vad Delay and Jitter The telephone industry standard specified in ITU-T G.114 recommends the maximum desired one-way delay be no more than 150 milliseconds. With a round-trip delay of 300 milliseconds or more, users might experience annoying talk-over effects. When using SIP trunks, you should consider the IP delay of both the enterprise and serv- ice provider networks. In some cases, centralized SIP trunk services cannot be effectively deployed because of the resulting increase in latency. A border element device at the cus- tomer premises is required to ensure that latency in the service provider network and enterprise network can be independently measured and controlled. An echo is the audible leak-through of your own voice into your own receive (return) path. The source of echo might be a TDM loop in the call path or acoustic echo that applies to all-IP calls. Acoustic echo can come from improper acoustic insulation on the phone, headset, or speakerphone (all Cisco IP Phones have an acoustic echo canceller) and is common on PC-based softphones. A border element demarcation point at a customer site can help you determine if a prob- lem with echo is occurring at the customer premises or in the service provider's network. Congestion Management When using a single connection for both voice and data, you should carefully consider congestion management (for example, queuing techniques such as Low-Latency Queuing [LLQ]) and bandwidth allocation to prevent data traffic from affecting the voice quality of SIP trunk calls. Chapter 7: Design and Implementation Considerations 129 The end-to-end voice quality experience of your SIP trunk calls depend on congestion management techniques in both your network and in the service provider's delivery net- work to your premises. A enterprise border element can help you determine in which net- work jurisdiction a problem lies. Voice-Quality Monitoring To ensure business class v