How to use freepbx--voxalot--spa3000 to make outbound fxo pstn calls?

I wish to know how to setup a spa3000 to work as outbound calls using fxo pstn line. VOIP -PSTN

I would use voxalot as the VOIP provider. account 31xxxxx

so I want to create a trunk in freepbx with voxalot account so the voxalot account would be the trunk in pbx.

how can I config the spa3000 using voxalot to connect with freepbx ?

instead of doiing SPA3000-----FreePBX directly
I want to use as SPA3000------Voxalot---------FreePBX

so I want to dial a prefix in freepbx that give me the troncal voip voxalot. and directly give pstn line in spa3000 to dial out using fxo ?

I am little confused if one voxalot can do the thing. since the spa3000 should be registered with voxalot and the freepbx would be registered with voxalot too. this is the way it works or how.
any info would be so mucha appreciate