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.
Pricing is set up to be predictable, which matters for service operators who hate variable-rate billing on a critical line. The Starter tier sits at $497 monthly and is built around the 100-to-250-calls-per-month operator: a single location, a single booking calendar, and the core AI conversation engine running the intake flow. Everything in Starter is configured during onboarding and tuned by a real human on the Human Add AI side before the agent ever picks up a live call.
Professional at $997 monthly is the tier most established businesses settle into. The volume allowance jumps to 750 answered calls, multi-location routing rules unlock so a single AI receptionist can route calls to the right office, and the integration footprint expands to include the deeper CRM hooks (Salesforce, HubSpot, Pipedrive, Clio Manage, Lawmatics, Dentrix Ascend, Open Dental, Jobber, Housecall Pro, ServiceTitan, FieldEdge, and twenty more). After-hours escalation rules are also standard at this tier.
Enterprise at $1,997 monthly is the high-volume tier with unlimited inbound calls, white-label phone numbers, a dedicated agent-tuning contact at Human Add AI, and direct routing to an on-call dispatcher with priority paths for emergency calls. Outbound calling is also enabled at this tier, billed at fourteen cents per outbound minute against a transparent monthly meter that any operator can cap from the dashboard.
None of the plans use seat counts, per-minute inbound charges, transcript fees, or annual commitments. The whole pricing structure is designed so the operator can predict the bill exactly, and the upgrade path is volume-driven rather than feature-gated. A business graduating from Starter to Professional pays more because they are taking more calls, not because they got locked out of something useful.
Common questions from service business operators
What does the caller actually hear when they dial my line?
The caller hears a custom greeting in the voice you picked during onboarding (warm, professional, or fast), followed by the agent asking how it can help. The conversation flows naturally, not as a menu tree. The agent introduces itself as part of your team on Starter and Professional plans, and uses your business name as the caller-facing identity on the Enterprise white-label tier. There is no holding music, no "press 1 for sales", and no robotic cadence.
How does the booking calendar integration handle conflicts?
The agent reads live availability against your calendar in real time, which means it never offers a slot that is already taken. If the calendar update happens between the moment the agent reads availability and the moment it confirms the booking (the rare race condition), the platform's conflict handler reverts the booking, texts the operator with both calls, and lets the operator decide which one keeps the slot. In practice this happens roughly once per ten thousand bookings.
What integrations exist for sending the lead summary to my CRM?
Native integrations cover Jobber, Housecall Pro, ServiceTitan, FieldEdge, mHelpDesk, Workiz, RazorSync, ServiceM8 in the field-service world, Salesforce, HubSpot, Pipedrive, Zoho, Close, Copper in the horizontal CRM world, Clio Manage, Lawmatics, Lawyaw, MyCase, Practice Panther, Smokeball in legal, Dentrix Ascend, Open Dental, Eaglesoft, Curve Dental in dental, and twenty other vertical-specific systems. Webhook handoffs cover everything else.
How does the platform handle emergency calls?
Emergency triage is configured during onboarding. The agent recognizes emergency signals in the caller's wording (specific keywords for the vertical, urgency tone, and explicit "this is an emergency" statements), routes the call directly to the on-call dispatcher number, and sends a high-priority SMS in parallel so the dispatcher can see the lead even if they miss the call. The emergency routing happens within the same call (no callback delay), which is critical for service business operators where the first business to answer wins the job.
What does the dashboard show?
The dashboard surfaces every inbound call (with searchable transcripts and recorded MP3), every booking, every SMS lead alert, the recovered-revenue math against your reported average ticket size, the conversion rate from call to booked appointment, the agent's confidence score per call, and the weekly summary email metrics. Operators on Professional and Enterprise also see the multi-location split and the outbound-call meter.
What is the SLA on agent tuning if something needs to change?
Standard tuning requests (script edits, new intake questions, calendar rule changes) are turned around inside 24 business hours on Starter, inside 8 business hours on Professional, and same-business-day on Enterprise. Operators can also self-serve most edits through the dashboard's knowledge base section, which propagates to the live agent within minutes.
How do I know it is actually working?
The weekly summary email shows the count of inbound calls, the count of bookings, the count of SMS lead alerts, the count of qualified leads texted to the dispatcher, and the recovered-revenue math based on the average ticket size reported during onboarding. The dashboard also has a "before / after" comparison view that runs against historical voicemail patterns if the operator imports them, so the lift is visible in dollar terms not just call counts.
Can I try it before committing?
Yes. The public demo line at (617) 812-5251 runs the production agent for a generic service business. Call from any phone and run a real scenario (an actual customer question, an actual scheduling constraint, an actual edge case). The agent will answer, qualify, and offer a real booking slot. The demo gives a faithful preview of what your own customers would experience. No signup, no form, no email collection on the demo path.
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.
