User's Manual

SME VoIP System Guide, Version 1.5
Proprietary and Confidential
Chapter: Network Operations
106
If the handset makes yet another handover, the RTP stream will still be relayed via the base station at
which, the call was established (here base station 1). This is illustrated as follows:
After handover to BS n the handset is located at BS n, and the RTP stream is relayed via BS 1.
15.7 Roaming
By roaming means the handset moves its SIP and DECT registration from one base station to another base
station. Roaming can only be initiated from idle.
Roaming does not immediately result in a new SIP registration, because this may cause a lot of unnecessary
signalling. Therefore, the handset will not perform a new DECT Location Registration until it has resided on
the same base station for a defined period of time. Since the SIP registration is initiated by the completion
of the Location Registration, a new SIP registration will also not be done until this procedure has completed
on a new base station. Thus, a handset must stay on the same base station as given in the rules stated
below, before a new SIP registration will be made.
Timing Criteria for Location Registration; or roaming will be initiated when:
1. Handsets lose contact to first base unit due to reset/power off/heavy DECT traffic.
2. After 5 minutes (configuration is possible) but before 5+2 minutes
a. The plus maximum 2 minutes will occur when service connection traffic is signaled at the same
time as location should happen. In this case the location registration procedure will be delayed.
If an incoming call arrives while the handset has moved to another base station (base station 2) but still not
performed a new Location Registration, the SIP call will arrive at the initial base station (base station 1), but
the RTP stream will be set up between base station 2 and the remote endpoint (refer to figure below).
Alternatively, in the case of an outgoing call, the SIP call will be established from the initial base station, and
the RTP stream will be set up between base station 2 and the remote endpoint.