OTP & Verification Messaging
One-time passcodes on dedicated high-priority routes - sub-3-second median delivery, automatic failover to voice OTP and flash call, AIT and fraud protection, and conversion tracking from send to successful verification.
< 3 s
Median OTP delivery
3
Channels: SMS, voice, flash call
98%+
Delivery on direct routes
What is OTP & Verification Messaging?
A one-time passcode that arrives late, or not at all, is a lost sign-up, an abandoned checkout or a locked-out customer. Dollu's OTP and verification messaging service is engineered around a single metric: the share of verification attempts that convert. Passcodes travel on dedicated high-priority routes - direct operator binds reserved for transactional traffic - with a median delivery time under three seconds and reserved capacity that is not shared with promotional campaigns.
When SMS is not the right channel, the platform switches automatically. If a passcode is undelivered within a threshold you set, or the destination is a market where SMS OTP is unreliable, the code is retried over voice OTP - a short text-to-speech call reading the digits in the recipient's language - or via flash call, where the last digits of a missed-call CLI serve as the code and the SDK verifies it without user input. Each channel is priced separately and you control the order and timing of fallback.
Verification traffic attracts fraud. Artificially inflated traffic (AIT), in which bots trigger OTP requests to numbers on premium or colluding routes, can burn a budget overnight. Our platform detects it in real time using velocity rules, number-range reputation, geographic anomaly checks and delivery-to-verification ratios, and blocks or challenges suspicious requests before they cost you money. Alerts, per-country caps and hard spend limits give you control, and our SOC reviews anomalies around the clock.
Conversion tracking closes the loop. Because verification calls back into the platform when a code is entered, we measure not just delivery but conversion - the share of OTPs that lead to a successful verification - per country, operator, route and channel. That data drives routing decisions automatically and gives your product and fraud teams a clear view of where users struggle. Banks, wallets, marketplaces, ride-hailing and social platforms use the service for sign-up, login, transaction confirmation and account recovery.
A2P SMS path: from your application to the handset.
Why choose Dollu for otp & verification.
The advantages of buying from a carrier that owns its network, interconnects and operations - rather than a reseller.
Higher conversion, fewer support tickets
Faster, more reliable passcodes mean more completed sign-ups, logins and payments, and fewer customers stuck on the verification screen contacting support.
Speed you can rely on
Reserved routes and separate queues keep OTP latency flat even while other customers run large campaigns, with per-country latency published in your dashboard.
A fallback for every scenario
Voice OTP and flash call reach users on networks that filter SMS, in markets with poor SMS delivery, or when a handset cannot receive text.
Fraud losses stopped in real time
AIT and bot-driven OTP pumping is detected within seconds and blocked or challenged, protecting your budget without punishing genuine users.
Insight down to the verification
Delivery and conversion analytics by country, operator, channel and route show where users succeed and where friction remains.
Compliance handled
OTP templates registered under DLT and equivalent regimes, sender ID protection and audit trails satisfy regulators and security teams.
Capabilities in detail.
Everything included with OTP & Verification Messaging - the platform features, options and controls you get from day one.
- 01
Priority OTP routing
Direct operator binds classified for transactional traffic, sticky routing per destination for predictable latency, reserved TPS headroom and automatic re-routing on latency or delivery degradation.
- 02
Voice OTP
Text-to-speech passcode calls in 30+ languages with digit repetition, DTMF confirmation and answering-machine detection; local CLIs in 100+ countries for higher answer rates.
- 03
Flash call verification
Zero-touch verification via a missed call from a number whose trailing digits form the code; SDKs for Android read and confirm the CLI automatically; instant fallback to SMS if unavailable.
- 04
AIT and fraud protection
Velocity limits per number, range and country; number-range and route reputation scoring; geo-anomaly detection; delivery-to-conversion ratio monitoring; automatic blocking and challenge rules.
- 05
Conversion tracking
Report each successful verification via API or SDK; dashboards correlate delivery, latency and conversion by country, operator, route and channel and feed the routing engine.
- 06
Verify API and SDKs
Hosted code generation, expiry, retry and rate limits; REST endpoints for send and check; SDKs for web, iOS and Android; webhooks for status and fraud events.
- 07
Template and sender management
Pre-registered OTP templates for DLT and other regimes, locale-specific message variants, protected sender IDs and content that resists phishing lookalikes.
- 08
Controls and alerts
Per-country and per-account spend caps, TPS limits, geo-fencing, allow and block lists and real-time alerts to your security team when anomalies are detected.
How it works.
From first conversation to live traffic - a tracked, engineer-led onboarding with a named owner at every step.
- Step 01
Define your flows
Tell us your target countries, expected verification volumes and preferred fallback order. We recommend channels per market based on delivery and conversion data.
- Step 02
Register and integrate
Templates and sender IDs are registered where required while you integrate the Verify API or plain SMS and voice endpoints, using test credentials and our handset lab.
- Step 03
Set protection rules
Configure velocity limits, spend caps and geo-fences. Default AIT rules are on from day one and tuned with your fraud team during the first weeks.
- Step 04
Measure and optimise
Report verifications back to the platform, review conversion by market with your account manager and let adaptive routing shift traffic to the best-converting channels.
Direct, premium or grey.
Where an SMS route class shows up: in delivery, in the sender ID your customer sees, in the truthfulness of the delivery receipt and in the compliance risk you carry.
| Dimension | Direct operator | Premium aggregated | Grey routesNot offered by Dollu |
|---|---|---|---|
| Delivery | Direct SMPP bind to the mobile operator; the highest and most consistent delivery | Via a vetted hub or Tier-1 aggregator holding operator agreements; high delivery with occasional re-routing | Via SIM farms or unauthorised international paths; unpredictable, filtered and blocked without notice |
| Sender ID | Registered alphanumeric ID, short code or long number preserved exactly | Registered sender ID normally preserved; may be substituted on a few destinations | Overwritten with a random numeric sender; your brand is invisible |
| DLR quality | Handset delivery receipts from the operator | Operator or hub receipts; reliable, occasionally delayed | Fake or aggregator-generated receipts; no proof of delivery |
| Compliance risk | Lowest - operator-approved, with DLT, 10DLC or sender-ID registration completed up front | Low - operator agreements in place; Dollu vets every hub it uses | High - breaches operator terms and local law; carries fines, blacklisting and lost sender IDs |
| Price position | Highest per message; the lowest cost per delivered, verified message | Mid | Lowest headline price; the hidden cost is failed OTPs, blocked traffic and brand damage |
Dollu does not sell grey routes. Every destination on our deck is direct operator or premium aggregated, and the route class is shown against each price so you know exactly what you are buying.
Who uses this and why.
Typical deployments across carriers, enterprises, platforms and contact centres.
Banks and payment providers
Transaction authorisation, login and card-activation codes with strict latency, DLT-registered templates and fraud controls.
Marketplaces and e-commerce
Sign-up and checkout verification where every second of delay costs conversion, with flash call for frictionless mobile flows.
Ride-hailing and delivery apps
Driver and rider onboarding at scale in emerging markets, with voice OTP where SMS is unreliable and AIT protection against bot sign-ups.
Social, dating and gaming
High-volume account creation with bot and SIM-farm protection to keep fake accounts out without adding friction for real users.
SaaS and enterprise login
Two-factor authentication and account recovery for global workforces with SMS, voice and flash call options and audit trails.
Technical & commercial specifications.
Key parameters at a glance. Ask us for the full service description and SLA document.
| Channels | SMS OTP, voice OTP (TTS in 30+ languages), flash call |
|---|---|
| Latency | Median < 3 s SMS delivery on direct routes; latency SLA available |
| Coverage | 220+ countries SMS; voice OTP with local CLIs in 100+ countries |
| Integration | Verify API (REST), SMPP, voice API, web/iOS/Android SDKs, webhooks |
| Fraud controls | AIT detection, velocity limits, geo-fencing, spend caps, block lists |
| Code handling | Hosted generation, 4–10 digits, configurable expiry and retries |
| Templates | DLT-registered and locale-specific; protected sender IDs |
| Analytics | Delivery, latency and conversion by country, operator, route, channel |
| Billing | Per attempt by channel and destination; prepaid or postpaid |
| Support | 24×7 NOC and SOC; P1 response ≤ 15 min; named account manager |
How Messaging is priced.
A2P, OTP and promotional SMS are priced per message by destination and route class - direct operator or premium aggregated. Wholesale SMPP decks for aggregators; RCS and WhatsApp per conversation or session.
We publish the model, not a public rate card - actual rates depend on destination, route class, volume and regulatory cost. See how every Dollu service is priced.
- Direct-operator and premium route tiers per destination
- Sender ID and DLT registration assistance included
- Volume-based discounts by monthly message count
- Two-way inbound priced per number
- RCS and WhatsApp Business per conversation or session
- Billing
- Per submitted message, itemised by destination and route; prepaid or postpaid
- Commitment
- None - month-to-month; volume commitments unlock better tiers
220+ destinations, 800+ operator connections.
Direct operator binds and premium aggregated routes into every major mobile network. Country guides explain the sender-ID rules, KYC and route options in the markets we are asked about most.
- Australia+61
- Brazil+55
- Canada+1
- France+33
- Germany+49
- Hong Kong+852
- India+91
- Mexico+52
- Netherlands+31
- Philippines+63
- Saudi Arabia+966
- Singapore+65
- South Africa+27
- United Arab Emirates+971
- United Kingdom+44
- United States+1
Sender-ID registration markets
In these destinations A2P traffic is scrubbed unless the sender is pre-registered. Dollu’s compliance desk prepares and submits the registrations before your first message.
- IndiaDLT entity, header and template registration
- UAESender IDs registered with e& and du under TDRA rules
- Saudi ArabiaSender IDs registered with stc, Mobily and Zain under CST rules
- SingaporeSMS Sender ID Registry (SSIR); UEN required
- PhilippinesSender-ID whitelisting with Globe, Smart and DITO
- United States10DLC brand and campaign registration
OTP & Verification - your questions answered.
The questions customers and carriers ask us most often before they interconnect. If yours is not here, our team answers within one business day.
Still have a question?
Ask our solutions teamRelated services.
Services customers commonly combine with OTP & Verification Messaging.
Cut verification failures this quarter.
Share your top verification markets and monthly attempts and we will benchmark delivery and conversion against your current provider in a two-week pilot.
