ve synchronization solution that should be cheaper, have greater site deployment flexibility, and can be controlled fully by the operator. ToP is a solution where phase syn- chronization can be obtained from the transmission network or backhaul network and can meet the aforementioned requirements. The ToP with phase synchronization solu- tion is based on the IEEE1588-2008 standard and follows the ITU-T profile. The relation- ship between IEEE1588-2008 and ITU-T requires some explanation. IEEE1588-2008 is 8 Deployment Aspects a standard which defines a set of methods and attributes to be used to achieve tim- ing accuracy in a packet network. It is not designed specifically for any application. It can be used as well in industry for automation purposes. For IEEE1588-2008 to be usable in real-life networks, the standard requires that a "profile" be created to meet the requirement of each application. ITU-T, which is a telecommunications standardization body, then takes the IEEE1588-2008 standard and defines a set of profiles to be used for telecommunications purposes. There are some telecom vendors that do not support ITU-T profiles and instead use their proprietary profile and claim IEEE1588-2008 com- pliance. Such equipment may have interoperability issues with equipment that support ITU-T telecom profiles. Operators should therefore strictly follow ITU-T profiles for the deployment of the ToP with phase synchronization solution. Apart from the set of func- tionalities defined in ITU-T that shall be implemented in network elements such as the base station, transmission equipment, and Grandmaster, ITU-T also defines network recommendations for phase synchronization deployment that operators can follow to ensure successful deployment of ToP with phase synchronization. An overview of the ToP solution is shown in Figure 8.25. The ToP with phase syn- chronization solution is an end-to-end solution which basically consists of following functionalities/network elements: The grandmaster clock is a network element that is 