Using multiple 3000s as a trunk?

[jsperkins]

I'm looking to use a pair of SPA-3000s as an FXO trunk so that an outgoing call can just jump on the first available line.

I used the wizard (very helpful, thx) and was able to set up one, named spa3k-pstn. It works great as a single line. But I'm not sure how to proceed from here, though, as I see mention of things like "the OUTGOING section of your extensions conf" yet I don't have that.

I'm getting a little tripped up on the terminology as well, when the documentation refers to trunks, groups, channels, etc.

Is it as simple as something like Dial(SIP/spa3k-pstn&SIP/spa3k-pstn2)?

Thanks for any assistance...