and narrow band codecs. WiFi phones have a high adoption at niche New features need to be offered to take phones locations. Their capabilities follow suit advantage of WiFi phone capabilities with the advancement of cellular phones. such as location-based services and WiFi roaming. Cellular Cell phones continue to be adopted as SIP trunk providers and consumers phone an alternative to enterprise phones. respond to this trend by requiring servic- adoption es that take into account how the trunk- ing changes with SNR capabilities. First, the services that offer basic connectivity with hairpinning are made available; the subsequent features are for SNR with optimized media. The final new feature is for SNR capabilities to occur within the network, under control of the SP instead of the enterprise. Feature Trends in SIP Trunking Within the Enterprise Trunking solutions are used extensively within an enterprise to connect to distinct realms of Unified Communications that are under the control of different call control entities. An example of this is an Automatic Call Director (ACD) that might be under the control of one group and the IP-PBX that might belong to a different group. In an enterprise, the need for trunks between entities is usually based on one of the following implementation challenges: Timing: When one solution such as an IVR has been upgraded and changed, other so- lutions, such as call control might not have been changed. This requires a trunking so- lution between these entities to compensate for the differences. Chapter 2: Trends in IP Telephony 21 Acquisitions: Many times occur when a single enterprise has acquired another enter- prise, and the most effective way to quickly transition that enterprise is to trunk the two call control entities together. Security: Within an enterprise often various levels of security exist that might require different levels of call control. Each individual device might have a different level of security in the two different areas, but they still have the need to comm