Twilio flow template - https://www.twilio.com/console/studio/flows/

flow.json

{
    "description": "Business number",
    "states": [
        {
            "name": "Trigger",
            "type": "trigger",
            "transitions": [
                {
                    "event": "incomingMessage"
                },
                {
                    "next": "check_opening_hours",
                    "event": "incomingCall"
                },
                {
                    "event": "incomingRequest"
                }
            ],
            "properties": {
                "offset": {
                    "x": 470,
                    "y": 20
                }
            }
        },
        {
            "name": "forward_call",
            "type": "connect-call-to",
            "transitions": [
                {
                    "next": "call_info",
                    "event": "callCompleted"
                },
                {
                    "next": "call_info",
                    "event": "hangup"
                }
            ],
            "properties": {
                "offset": {
                    "x": 620,
                    "y": 570
                },
                "caller_id": "{{flow.channel.address}}",
                "noun": "number",
                "to": "+420123456789",
                "timeout": 30
            }
        },
        {
            "name": "split_based_on_is_open",
            "type": "split-based-on",
            "transitions": [
                {
                    "next": "closed_message",
                    "event": "noMatch"
                },
                {
                    "next": "forward_call",
                    "event": "match",
                    "conditions": [
                        {
                            "friendly_name": "If value equal_to true",
                            "arguments": [
                                "{{widgets.check_opening_hours.parsed.isOpen}}"
                            ],
                            "type": "equal_to",
                            "value": "true"
                        }
                    ]
                }
            ],
            "properties": {
                "input": "{{widgets.check_opening_hours.parsed.isOpen}}",
                "offset": {
                    "x": 250,
                    "y": 370
                }
            }
        },
        {
            "name": "closed_message",
            "type": "say-play",
            "transitions": [
                {
                    "event": "audioComplete"
                }
            ],
            "properties": {
                "offset": {
                    "x": 100,
                    "y": 690
                },
                "loop": 1,
                "say": "We're closed. Please call during working hours."
            }
        },
        {
            "name": "call_info",
            "type": "send-message",
            "transitions": [
                {
                    "event": "sent"
                },
                {
                    "event": "failed"
                }
            ],
            "properties": {
                "offset": {
                    "x": 730,
                    "y": 880
                },
                "service": "{{trigger.message.InstanceSid}}",
                "channel": "{{trigger.message.ChannelSid}}",
                "from": "YOUR_SMS_CAPABLE_NUMBER",
                "to": "YOUR_CELLPHONE_NUMBER",
                "body": "Last caller number: {{contact.channel.address}}"
            }
        },
        {
            "name": "check_opening_hours",
            "type": "make-http-request",
            "transitions": [
                {
                    "next": "split_based_on_is_open",
                    "event": "success"
                },
                {
                    "next": "forward_call",
                    "event": "failed"
                }
            ],
            "properties": {
                "offset": {
                    "x": 610,
                    "y": 170
                },
                "method": "POST",
                "content_type": "application/json;charset=utf-8",
                "body": "{\n  \"timezone\": \"Europe/Berlin\",\n  \"workdays\": [\n    \"Mon\",\n    \"Tue\",\n    \"Wed\",\n    \"Thu\",\n    \"Fri\"\n  ],\n  \"opening_hours\": [\n    [\n      9,\n      16\n    ]\n  ]\n}",
                "url": "https://openinghours.vercel.app/"
            }
        }
    ],
    "initial_state": "Trigger",
    "flags": {
        "allow_concurrent_calls": true
    }
}