SMS channel
Twilio + Telnyx + Bandwidth A2P 10DLC with STOP keyword auto-DNC.
- ·Twilio · Telnyx · Bandwidth A2P 10DLC support
- ·RFC 8058-style STOP / UNSUBSCRIBE keyword detection
- ·Auto-DNC across every channel on opt-out
- ·Per-number daily and hourly caps + quiet hours
- ·TCPA-compliant by default — never the operator’s job
- ·Two-way: replies land in Unibox alongside email
Why most cold SMS gets blocked at the carrier
US carrier filtering blocks 90%+ of unregistered traffic in 2026. India's TRAI DLT regime auto-rejects messages without a registered header. STOP keyword laws (TCPA in the US, DPDP-aligned in India) carry per-violation damages that wipe out a quarter on one slip.
- Delivery rate dropped below 60% on a number that worked yesterday
- STOP came in but the next outbound still went out (lawsuit risk)
- Carrier suspended the number with no warning
- TCPA complaint letter from a state AG
The detail.
10DLC is not optional — and we know it
US carrier filtering blocks 90%+ of unregistered traffic in 2026. Autocloz refuses to dispatch SMS through an account whose 10DLC brand and campaign SIDs are not present, surfaces registration status on the account detail page, and warns operators before the first send.
STOP detection — a hard rule, not a heuristic
Every inbound SMS runs through detect_opt_out() with the carrier-recognised STOP keyword set. A match writes a DNC row immediately, tagged with the channel <strong>*</strong> wildcard so the next outbound to that recipient — on email, LinkedIn, WhatsApp, or call — is also blocked.
Replies feel like a real conversation
Two-way SMS lands in the Unibox alongside email and WhatsApp, AI-tagged for intent, with the lead’s full timeline one click away. Reply from the keyboard; the dispatcher honours the per-account cap.
Bring your own — or pick from the supported set.
The rules that keep your account alive.
Every rule below is enforced before any outbound action. The compliance gate either passes or it doesn’t dispatch.
- Refuse to dispatch through unregistered 10DLC / DLT sendersWhy: US carriers block 90%+ of unregistered traffic; India auto-rejects. Sending = wasted spend AND reputation damage.
- Inject 'Reply STOP to opt out' into every message body when require_consent=ONWhy: TCPA hard rule. Forgetting it once = lawsuit class certification.
- Auto-DNC on STOP / UNSUBSCRIBE / CANCEL / QUIT / END / OPTOUTWhy: These are carrier-recognised opt-out keywords; honouring all of them is required, not optional.
- Cross-channel DNC propagationWhy: If a recipient says STOP on SMS, they cannot legally be contacted on WhatsApp (same TCPA framework). Autocloz writes the wildcard '*' DNC row automatically.
- Quiet hours in recipient's timezone, default 9 PM – 9 AMWhy: Messages outside the 8 AM–9 PM window are TCPA violations even with prior consent.
A real sequence using this channel — day by day.
- Day 0Email + SMS opener comboSMS arrives 30s after email open · 'just sent you a note' framing
- Day 2SMS reminderOnly if email_event.opened == false · short, value-first
- Day 5WhatsApp escalationIf still no reply · same template-gated rules apply
- Day 7Final SMS with breakup'Last note from me' framing; high reply rate
- Day 9Re-engage 30d laterAuto-snoozed; surfaces if any channel fires intent
“We caught a STOP from a prospect, and the system instantly blocked them across all five channels. That feature alone is worth the subscription.”
Specific to this channel.
Do I need 10DLC registration to send SMS in the US?+
Yes — US carriers (Verizon, AT&T, T-Mobile) block 90%+ of unregistered A2P traffic. Autocloz refuses to dispatch through an unregistered number; we surface registration status on the account detail.
What about India DLT?+
Same idea — TRAI requires entity + header registration for promotional SMS. We won't dispatch through an unregistered Indian sender.
Will replying STOP really opt the recipient out everywhere?+
Yes — STOP writes a DNC row with channel='*' (wildcard), so the next outbound on email, WhatsApp, call, or LinkedIn is also blocked. This is the legally safe default.
Can I send marketing SMS in India?+
Yes, but only via a registered DLT entity + approved template content. Promotional traffic outside 9 AM – 9 PM IST is filtered automatically.