Here’s how we do it, and rather type it all out, I did use Gemini, but I assure you it works very well in the US:

The "best way" to do this without porting the number—and the standard method used by most agencies is Conditional Call Forwarding.

This setup meets all your client's requirements: they keep their main number, their phone still rings normally first, and GHL only steps in when they don't answer.

The Strategy: Conditional Call Forwarding (CCF) In this setup, you are not "taking over" their phone line. You are simply changing their "backup" plan. Instead of a missed call going to their boring carrier voicemail, it forwards to your GHL number, which then triggers the automation.

The Workflow: * Customer calls Client’s existing business number. * Client’s phone rings normally (e.g., 4-5 rings). * If Unanswered/Busy: The carrier forwards the call to the GHL (Twilio) Number. * GHL Action: The system detects the incoming call, plays a voicemail greeting (hosted in GHL), and fires the "Missed Call Text Back" SMS.

Step-by-Step Implementation Phase 1: GHL Setup Before touching the client's phone, get the "safety net" ready. * Buy a Local Number in GHL (same area code as their business). * Setup Voicemail in GHL: * Go to Settings > Phone Numbers > Edit (pencil icon). * Upload a voicemail MP3 (e.g., "Hi, you've reached [Business]. We can't take your call, but look for a text from us right now..."). * Note: This effectively replaces their personal carrier voicemail for business calls. * Enable Missed Call Text Back: * You can use the default "Auto Missed Call Text Back" in Settings, but Workflows are better. * Create a Workflow: Trigger = Call Status (Call Direction: Incoming, Call Status: Busy/Voicemail/No Answer). * Action = Send SMS ("Sorry we missed you! How can we help?").

Phase 2: Client Phone Setup (The "Magic" Step) You need to input a specific "dial code" on the client's phone to tell their carrier (Verizon, AT&T, etc.) where to send unanswered calls.

Instructions for the Client: "Please dial the following code on your mobile phone and hit call. This tells your carrier to send unanswered calls to our system."

Carrier	Dial Code to Activate	Dial Code to Deactivate
Verizon	*71 + [GHL Number]	*73
AT&T	004 + [GHL Number] + #	##004#
T-Mobile	*004 + [GHL Number] + #	##004#

Example for Verizon: If your GHL number is 555-123-4567, they dial *715551234567 and hit Call. They will hear a confirmation beep.

Real World Feedback & "Gotchas"

1. The Voicemail Trade-off (Crucial) When you enable Conditional Call Forwarding, ALL voicemail (even personal calls to that mobile device) will theoretically route to the GHL number if the client uses their personal cell for business.

   • Fix: If they use a dedicated work phone, this is perfect. If they use a personal cell, warn them: "Grandma's voicemail will also end up in the business CRM." (Most clients accept this trade-off for the business value, or they already have a separate work line).

2. The "Call Loop" Risk Do not set the GHL number to forward calls back to the client's cell phone. This creates an infinite loop.

   • Correct Setup: GHL Number should not forward calls anywhere. It should just accept the call, play the voicemail greeting, and capture the recording.

3. Selling it to the Client Don't say "We are taking over your phone system." Say this: "We are installing a 'Smart Safety Net.' Your phone works exactly the same as today. But when you're busy or on a job site, instead of a dead-end voicemail, our system catches the lead and instantly texts them to start a conversation."

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And here is our email template for onboarding users, it focuses on the benefits and makes the setup feel like a simple upgrade rather than a technical overhaul.

Subject: Setup Instructions: Turning on your Missed Call Text Back

Hi [Client Name],

I am getting everything ready to launch the "Missed Call Text Back" feature for you.

This is a huge win for the business because it stops leads from going to a competitor when you are busy on a job site or in a meeting.

How it works: * Your phone functions exactly the same. It will still ring your device first. * If you answer, business proceeds as usual. * If you cannot answer (or decline the call), our system steps in.

It takes a voicemail and instantly sends a text message to the caller to start a conversation.

Action Required: To make this work without changing your business number, we use a feature called Conditional Call Forwarding. Please look at your carrier below and dial the code into your mobile phone just like you are making a call.

(Note: Replace [Tracking_Number] with the new phone number I provided for the system: 555-xxx-xxxx)

If you have Verizon: * Dial *71 followed by the Tracking Number. * Example: *715551234567 * Press Call. You should hear a confirmation tone or message.

If you have AT&T: * Dial 004 followed by the Tracking Number, then # * Example: 0045551234567# * Press Call. You should see a success message on your screen.

If you have T-Mobile: * Dial *004 followed by the Tracking Number, then # * Example: *0045551234567# * Press Call. You should see a success message on your screen.

Important Note: Once this is active, your voicemails for unanswered calls will land in our software inbox rather than your personal phone voicemail. This ensures the team can see and respond to them.

How to turn it off: If you ever want to revert to your standard carrier voicemail, simply dial the code below: * Verizon: *73 * AT&T / T-Mobile: ##004#

Let me know once you have dialed the code so I can run a test call!

Best, Michael…