Full SIP Trunking between NEC SL1000 and Asterisk

The setup was done between an NEC SL1000 and Asterisk flavour FreePBX. The easiest way to explain the setup is to provide a table showing the interacting commands between the two PBX's:

Asterisk (192.168.0.2)	SL1000 (192.168.0.3)
Outgoing: Trunk name: xxxxx host=192.168.0.3 username=xxxxx fromuser=xxxxx secret=xxxx type=peer qualify=yes context=from-trunk	Incoming: 10-23-02 = 192.168.0.3 10-30-02 = as per asterisk 10-30-03 = as per asterisk
Incoming: User context = xxxxx secret=xxxx type=user context=from-trunk	Outgoing: 10-28-04; 10-36-UserID,AuthID; 14-12. 10-36-Password; 14-12.