GSMA recently have proposed a new Vo LTE roaming architecture
S8 HR
as second candidate for Vo LTE roaming besides RAVEL. Unlike previous architecture
S8 HR does not require the deployment of an IMS network in VPLMN. It is only need IMS network deployment in HPLMN and bilateral LTE roaming agreement. S8 HR is advantageous because it shortens time-to-market and provides service universally without having to depend on the capability of VPLMN. In this article
S8 HR technical characteristics
basic call controls
technology field trials and performance comparison are discussed in detailed.