I was reading this guide https://support.flowroute.com/093183-Configure-an-Asterisk-PBX
It specifies a tech prefix. I suggest you to add your assigned tech prefix to the carrier config like
"prefix": "<PREFIX-NUMBER>",
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I was reading this guide https://support.flowroute.com/093183-Configure-an-Asterisk-PBX
It specifies a tech prefix. I suggest you to add your assigned tech prefix to the carrier config like
"prefix": "",