Simple SLA with Cisco SPA500 Series


I am very new to Asterisk, and am looking for help implementing a simple SLA configuration on my Cisco SPA500 series phones.

I am using a VoIP provider (SIP) and SIP for the phones.

Can someone give me a very simple setup for two stations? I see everything on the internet and the Definitive Guide, but I cannot figure out the link between the files and the stations.

So, I get how to make a phone register to the server, and the server to register to the VoIP. I get incoming and outgoing calls going just fine. When I try to turn that over into an SLA trunk, I get lost. I can’t figure out what talks to who, where, in which file (SLA, SIP, and extensions).

Any and all help is greatly appreciated.