Autoassign sip-trunk

Good day to all.
I have asterisk and freepbx 9.0. I have 4 external sip trunks.
In outbound routes I create “external-calls” route. In “Trunk Sequence for Matched Routes” i assign my sip trunks like

  • sip-trunk1
  • sip-trunk2
  • sip-trunk3
  • sip-trunk4

When i make outbound call i call from sip-trunk1. The second call drops by asterisk with error circuit si busy. How can i get autoassign free sip-trunk to out calls?
Maybe i missing something?