The introduction of number portability (NP) in the mid-1990s was a revolutionary concept as it allowed subscribers to retain their phone number when moving from one service provider to another, between service types or categories or from one geographic region to another.
According to Analysys Mason, 65 countries have deployed NP since then, with 10 more slated to roll it out in 2009-2010.
An essential element in any NP solution is the NP server, which is the node or nodes that maintain subscriber status information and provide real-time routing. The server can be implemented as a stand-alone service control point (SCP) or integrated with a signal transfer point (STP).
The number range owner network is the network that "owned" the number before NP. The network from which a subscriber is porting is called the "donor" network, and the network to which the subscriber is ported is the "subscription or recipient" network.
Key network elements in an NP domain
The server can be implemented as a stand-alone service control point (SCP) or integrated with a signal transfer point (STP).
Four NP call/message routing schemes have evolved: all call query (ACQ), query on release, return to pivot or call drop-back, and onward routing.Most frequently, operators now use onward routing and ACQ.