Call processing
An alternative to the single Communication Manager configuration is to have one logical Communication Manager system, but have two Communication Manager servers connected with QSIG or standard Communication Manager TIE trunk connection using ISDN or IP trunks. This increases the total capacity of the solution and retains the optimization of having only one Communication Manager system with multiple SES home servers. Customers with existing systems of Communication Manager servers would likely have the QSIG infrastructure already in place before they upgrade to SIP.