Human Add AI help center covers call forwarding setup for every major US carrier (Verizon, AT and T, T-Mobile, Spectrum, Comcast, RingCentral, Google Voice, OpenPhone, and twelve more), PWA install instructions for the mobile dashboard, knowledge base editing, and account management. Most setup guides take under five minutes to complete.
T-Mobile supports both "always forward" (unconditional) and "forward only sometimes" (conditional) with different star codes. This guide covers every one.
The quick version
On your T-Mobile phone, open the dialer and enter **21* followed by the 10-digit number you want calls forwarded to, then press call. To turn forwarding off, dial ##21#.
Step-by-step: enable call forwarding on T-Mobile
1
Open the phone dialer app on the T-Mobile line you want to forward. You'll enter a short code the same way you'd enter a phone number.
2
Type**21* followed immediately by the 10-digit number you want calls forwarded to. No spaces, no dashes, no "+1". Example: **21*5551234567.
3
Press the call/send button. You'll hear a short confirmation tone or a brief recorded message, then the call ends automatically.
4
Test it. From a different phone (or ask a friend), call your T-Mobile number. It should ring at your forwarding destination, not your cell.
To turn forwarding off
Open the dialer, enter ##21#, and press call. You'll hear a confirmation. Your line is back to normal immediately.
Conditional forwarding (only when you don't answer)
Sometimes you want to handle some calls yourself and forward the rest. "Conditional" call forwarding routes calls only when your line is busy, unanswered, or unreachable. T-Mobile supports four separate conditional codes:
**67*NUMBER# - forward when your line is busy (##67# to disable).
**61*NUMBER# - forward when you don't answer (##61# to disable).
**62*NUMBER# - forward when unreachable / no signal (##62# to disable).
**004*NUMBER# - sets all three conditional rules at once to the same number (##004# to disable).
If you want every call to forward regardless of state, stick with **21*.
Using the T-Mobile app instead
The T-Mobile app lets you manage forwarding under Account → your line → Profile settings → Call forwarding. Toggle on, enter the destination number, save. This is the safer option if you're worried about typing a code wrong.
Things worth knowing
T-Mobile also supports legacy *72 / *73 codes on some lines, but the **21* GSM format is more reliable network-wide.
Metro by T-Mobile uses the same codes.
Wi-Fi calling and call forwarding can sometimes conflict. If forwarding isn't working as expected, try briefly turning off Wi-Fi calling, test, then turn it back on.
No cost for forwarding on T-Mobile Magenta, Go5G, or Essentials plans.
Forwarding to an AI receptionist?
The whole reason you're reading this is probably to stop missing calls. If you're setting up call forwarding to send calls to a voice assistant, an answering service, or an AI, the steps above are the same - you just enter their number as the forward-to destination. Human Add AI gives you a dedicated AI receptionist that answers 24/7, captures every caller's intent, and texts you the details. Try it free for 7 days →
Troubleshooting
You hear an error or fast busy signal. Double-check you entered a valid 10-digit number with no extra characters. Some T-Mobile plans (pre-paid especially) don't include call forwarding - if it still won't set up, call T-Mobile and ask them to enable "call forwarding" on your line.
Calls still ring your cell. Forwarding can take up to a minute to activate. Wait 60 seconds and test again. If it's still not working, dial ##21# to clear it, then redo the enable code.
You want to stop forwarding but don't remember the code. Dial ##21# from the forwarded line. That's the universal "cancel all forwarding" code on most networks.
Voicemail is picking up before the forward kicks in. That's usually because your voicemail delay is set shorter than the forward. If you want forwarded calls to always get through, use unconditional forwarding (**21*) instead of conditional.
Every Human Add AI trial gives you a dedicated local phone number with a fully custom AI receptionist on the other end. Free for 7 days, $10 refundable activation.
Starter is $497 a month for up to 200 calls, with one AI assistant and one business number. Professional is $997 a month for unlimited calls and up to 3 AI assistants, and connects to your CRM (the software you track customers in). Enterprise starts at $1,997 a month. Every plan answers 24/7, books appointments and texts you each lead. Start with a 7-day free trial ($10 activation fee, credited to your first bill), backed by a 30-day money-back guarantee. See full pricing or call the demo line at (617) 812-5251.
How the platform fits into the daily operations rhythm
Once Human Add AI is live, the daily operations rhythm for a service-business owner changes in a small number of concrete ways. The phone stops being something the owner thinks about during business hours. Voicemail goes away because every call gets answered live. The booking calendar fills with new appointments without anybody manually keying them in. SMS alerts arrive on the on-call dispatcher's phone for every qualified lead, with the caller name, number, and intake summary already attached.
The weekly summary email arrives every Monday morning with the call count, the booking count, the SMS lead count, and the recovered-revenue math. Most operators stop opening the daily call list after the first month because the system has earned trust at that point and the weekly summary is enough. The dashboard remains available for the rare investigation: an operator drilling into a specific booking, a customer calling back about a previous conversation, or a tuning request to refine the agent script.
The change in the operator own time is the second-order effect that most operators report as the biggest unexpected value. Sixty to ninety minutes per day of phone qualification time gets returned to the operator, which can be spent on revenue-generating work, on team management, or on actually taking a lunch break. The dollar value of that time alone usually exceeds the platform monthly price for any owner-operator profile.
What the platform does not try to do
Being clear about scope matters because every platform has things it intentionally does not do, and the operator should know those up front. Human Add AI does not try to be a unified CRM. It integrates with the CRM the operator already uses (Jobber, Housecall Pro, ServiceTitan, Salesforce, HubSpot, Clio, Dentrix, twenty more) but does not try to replace it. The platform sends the right data into the right system; it does not try to be the system of record.
It also does not try to be a marketing automation tool. There is no email sequence builder, no landing-page builder, no funnel analytics dashboard. The platform handles the phone (inbound and outbound calls plus SMS lead alerts) and stops there. Operators who want marketing automation use a dedicated tool for that and integrate the two via webhook.
It does not try to be a workforce management platform. There is no shift scheduling, no time tracking, no payroll integration. The platform delivers leads to the operator and the operator dispatches them through whatever workforce tools they already use. The narrow scope is intentional: Human Add AI is built to be the best at one specific job, not adequate at five jobs.
