Oct 21, 2009

The Smart Phone Control Protocol (SPCP)

The Smart Phone Control Protocol, or SPCS, is an addition to the Simple Call Control Protocol (SCCP) that is only supported on the CP-500 phones and the SPA525 phone.

79XX phones register with their SCCP call control using a proprietary handshake that consists of a series of messages. During the registration phase a number of things happen:

1. Phone (Station) sends a Registration Request

2. Request is acknowledged by the Call Control (CME/UC500)

3. Capabilities are advertised

4. Button template, Softkeys, Line Status, Display message, Speed dials Time and date are requested by the phone and sent by CME/UC500

When the phone is a 500 series phone, two additional messages precede all this handshake, namely an SPCP Token Request and an SPCP Token Acknowledgement (if successful) or Token rejection (if unsuccessful). A Token ACK can only be sent by UC500, while an ISR will always send a Token Reject. This prevents the phone from registering to any call control different than UC500.

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