I spent a few days looking into how to get a VOIP number in Europe and it wasn't as easy as I thought. That's why I created this article to help people who run into the same problem.

This guide will walk you through building a working VoIP setup: a Twilio phone number for voice and SMS, routed through a SIP Sipnetic app on your Android or IOS, with call/message/voicemail logic handled by Cloudflare Workers. All for an European number.

This is for a technical audience.

What you'll end up with

• A Twilio number that can make and receive calls through Sipnetic.
• Incoming SMS and voicemail will be forwarded to your email, with an auto-reply nudging people to WhatsApp/Signal

Why would you want a VOIP number?

• Cheaper since it calls over the internet vs over landlines.
• More features like call forwarding, voicemail-to-email, auto-attendants/IVR menus, call recording, ring groups, analytics, video calling, SMS, and CRM/helpdesk integration.
• Easy to replace/rotate/have multiples/hand-out to strangers
• No need for a SIM card in your phone anymore, so better for privacy

Prerequisites

• A Twilio account with an approved regulatory bundle (required for many EU numbers).
• The Sipnetic softphone app (iOS/Android).
• A free Cloudflare account to set-up workers to handle the requests
• A Mailjet account and API key (or swap in any transactional email API)

1. Set up and create your regulatory bundle in twillio

Products & Services -> Trust Hub → Registrations -> Regulatory Compliance. This will take a while but is standard KYB/C.

2. Buy a number

Go to Products & Services -> Numbers & Senders → Overview → Set up a new phone number. Be sure to choose Active Region: Ireland (IE1). You don't want your European phone calls to be handled by a US-based server because of speed. Buy a local number.

3. Create a Credential List + SIP Domain

Go to Products & Services -> Voice → SIP Domains. Ensure everything is in Ireland (IE1)

• Under Credential List, create/attach a Credential List (username + password). This will be used by the Sipnetic app to login.

• Create a SIP domain. e.g. yournumber.sip.twilio.com.

4. Handle outgoing calls

Create a Cloudflare Worker in Cloudflare

1. Workers & Pages → Create → Start with Hello World" → Deploy
2. Change worker name to outgoing.*
3. Click Edit code, replace the placeholder, Save and deploy

export default {
  async fetch(request) {
    const formData = await request.formData();
    let to = formData.get('To');

    // Defensive: strip any stray prefix some SIP clients add before the +
    const plusIndex = to.indexOf('+');
    if (plusIndex > 0) to = to.substring(plusIndex);

    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Dial callerId="+YOUR_TWILIO_NUMBER">
        <Number>${to}</Number>
    </Dial>
</Response>`;

    return new Response(twiml, { headers: { 'Content-Type': 'text/xml' } });
  }
};

Add this link as "Webhook URL'" under SIP Domain → Details -> Call control configuration → A call comes in.

5: Handle incoming calls + voicemail (attached to the phone number)

export default {
  async fetch(request) {
    const formData = await request.formData();
    const from = formData.get('From');

    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Dial timeout="20" callerId="${from}">
        <Sip>sip:YOUR_SIPNETIC_USERNAME@YOUR_DOMAIN.sip.twilio.com</Sip>
    </Dial>
    <Say voice="Polly.Joanna">Sorry, I can't take your call right now. Please leave a message after the tone.</Say>
    <Record maxLength="120" playBeep="true"
        recordingStatusCallback="https://voicemail.YOUR-SUBDOMAIN.workers.dev"
        recordingStatusCallbackMethod="POST" />
    <Say voice="Polly.Joanna">Thank you, goodbye.</Say>
</Response>`;

    return new Response(twiml, { headers: { 'Content-Type': 'text/xml' } });
  }
};

Attach this as Webhook under Products & Services -> Numbers & senders -> Overview -> Phone Numbers -> Inventory (method: Webhook, POST). Click on your number, then "Voice and emergency address" and then "edit configuration details" and your region

For voicemail, create another worker:

export default {
  async fetch(request, env) {
    const formData = await request.formData();
    const from = formData.get('From');
    const transcriptionText = formData.get('TranscriptionText');
    const recordingUrl = formData.get('RecordingUrl');
    const duration = formData.get('RecordingDuration');

    await fetch('https://api.mailjet.com/v3.1/send', {
      method: 'POST',
      headers: {
        'Authorization': 'Basic ' + btoa(`${env.MAILJET_API_KEY}:${env.MAILJET_SECRET_KEY}`),
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        Messages: [{
          From: { Email: env.MAILJET_SENDER_EMAIL, Name: "Voicemail" },
          To: [{ Email: env.FORWARD_TO_EMAIL, Name: "Me" }],
          Subject: `Voicemail from ${from} (${duration}s)`,
          TextPart: `${transcriptionText}\n\nRecordings: https://1console.twilio.com/account/YOUR_ACCOUNT/ie1/logs/voice/call-recordings`,
          HTMLPart: `<p>${transcriptionText}</p><p><a href="https://1console.twilio.com/account/YOUR_ACCOUNT/ie1/logs/voice/call-recordings">Go to recordings</a></p>`
        }]
      })
    });

    return new Response('OK');
  }

Attach this as Webhook in the script above (for handling incoming calls), under recordingStatusCallback

6. Handle incoming SMS → forward to email

export default {
  async fetch(request, env) {
    const formData = await request.formData();
    const from = formData.get('From');
    const body = formData.get('Body');

    await fetch('https://api.mailjet.com/v3.1/send', {
      method: 'POST',
      headers: {
        'Authorization': 'Basic ' + btoa(`${env.MAILJET_API_KEY}:${env.MAILJET_SECRET_KEY}`),
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        Messages: [{
          From: { Email: env.MAILJET_SENDER_EMAIL, Name: "SMS Forwarder" },
          To: [{ Email: env.FORWARD_TO_EMAIL, Name: "Me" }],
          Subject: `SMS from ${from}`,
          TextPart: body
        }]
      })
    });

    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Message>Please reach me on WhatsApp or Signal instead — this number doesn't support replies.</Message>
</Response>`;

    return new Response(twiml, { headers: { 'Content-Type': 'text/xml' } });
  }
};

Attach this Webhook under Products & Services -> Numbers & senders -> Overview -> Phone Numbers -> Inventory (method: Webhook, POST). Click on your number, then "Messaging" and then "edit configuration details" and your region

Setting secrets

On each Worker's page: Settings → Variables and Secrets → Add, and add these as Secret type (not plain text):

SMS Worker:

• MAILJET_API_KEY
• MAILJET_SECRET_KEY
• MAILJET_SENDER_EMAIL (must be a verified sender in your Mailjet account)
• FORWARD_TO_EMAIL Your email address where you want to receive voicemail/sms

7. Download & Set-up Sipnetic app

Add a new SIP account with:

• Server: YOUR_DOMAIN.sip.twilio.com (for registration/incoming)
• Username/Password: that you created in Twilio Credential List

Once registered (status shows green/connected), you can place and receive calls!

Congrats, you now have a VOIP number that can send/receive calls, record voicemail and receive sms to email.

Here's a quick checklist to test everything now;

Testing checklist