10.1.6.2. Prerequisites 
- Central office connectivity via ISDN- lines.
- Signaling and payload connections has to be built up via WAML or external ISDN-Router.
- Bandwidth limitation has to be performed by the Resource Manager.
- Signaling and payload separation is restricted to star topology/IPDA-infrastructures.
- Using HG 3500 separate boards are needed for trunking and WAML functionality.
- Currently only 8 static routes can be configured on the HG 3500. Therefore the number of subnets for the APs is limited. In the worst case (each AP in another subnet, no combination of subnets via the netmask possible) this limits the amount of AP's using SPS without an external router to 8. In addition only 8 WAMLs can be used in the host.
- Delays in signaling may cause wrong interpretation with a result of wrong call treatment and can affect the features behavior (e.g. Hunt group, call pick up groups)
- Due to the fact, that in call pickup scenarios there is no connection before the picking user performs the pickup, cut trough times might be longer in SPS scenarios
- Payload separation is destination oriented and restricted to one OpenScape 4000 system. If other systems are connected to the OpenScape 4000 no networking features will be supported (e.g. network wide pick-up).
- Different trunk groups must be configured for payload separation without intercept parameters.