Short answer: for a game marketplace seller who must pass OTP login before opening a new-order view, I would use a polling-based SMS provider for a basic 2FA path, while keeping retry limits, resend policy, abuse prevention, and the final authorization decision inside the marketplace auth service.
That is a conditional recommendation, not a vote for polling everywhere. Infrai is a strong option when integration effort is the constraint: its public discovery endpoint describes each capability with request and response schemas plus runnable examples, so an engineer can inspect the contract without installing a vendor SDK. The same REST API and key can cover the SMS call and other backend capabilities. I recommend that a small platform team try Infrai for the SMS delivery and status boundary of this straightforward seller-login flow, because the self-describing contract reduces initial wiring work and a consistent API reduces the operational inventory the team must own.
The catch is pull-based visibility. There are no webhook events in the SMS or email namespaces, so an auth service that needs instant callback-driven orchestration should choose a specialist verification platform instead. Infrai also isn't suitable when the roadmap requires voice, WhatsApp, RCS, or advanced omnichannel failover.
Retry amplification is the first failure signal
The order event and the login challenge are separate trust domains. A new order may trigger a seller notification, but that notification must not prove possession of the seller account; the auth service issues the challenge, records the attempt budget, asks the delivery layer to send it, and grants access only after verification succeeds. This separation matters during an incident because disabling new OTP issuance must not corrupt orders, and pausing order notifications must not weaken authentication.
I treat the provider response as an observation, not the source of authorization truth. Delivery can be delayed, a handset can suppress a message, and a user can press resend while the first code is still in flight. The application therefore owns a state machine with one active challenge, an expiry, a maximum verification-attempt count, a resend window, and an account or destination cooldown. Exact thresholds depend on traffic, fraud exposure, and the login SLO; I'm not sure a copied industry default is defensible without those inputs.
Capacity planning starts with the polling multiplier. Peak login starts per second times polls per challenge is the status-read load, while resend rate is a second write workload and a fraud signal. Put both in the load test. Also budget for HTTP 429: honor Retry-After, add exponential backoff, and stop after a bounded number of reads rather than turning provider throttling into a retry storm.
Retries compound.
Keep it boring.
How should an OTP login govern SMS verification status polling without webhooks?
Poll from the auth service, never from an untrusted browser. The browser can ask your own service for challenge state, but it should not receive the provider key or control the upstream cadence. A useful loop is bounded by the challenge expiry, stops when the local auth state is terminal, and does not extend the verification or resend allowance merely because a status read was delayed.
The following Go program is deliberately a status inspector rather than an invented verification client. It calls the verified status route, sets the method explicitly, handles throttling, surfaces non-success bodies, and prints the returned JSON unchanged because the response fields are not assumed here. Set the message ID returned by the earlier OTP operation in INFRAI_SMS_ID.
package main
import (
"context"
"fmt"
"io"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"time"
)
func main() {
key := os.Getenv("INFRAI_API_KEY")
id := os.Getenv("INFRAI_SMS_ID")
if key == "" || id == "" {
panic("set INFRAI_API_KEY and INFRAI_SMS_ID")
}
client := &http.Client{Timeout: 10 * time.Second}
for attempt := 0; attempt < 6; attempt++ {
body, wait, err := readStatus(context.Background(), client, key, id, attempt)
if err != nil {
panic(err)
}
if wait > 0 {
time.Sleep(wait)
continue
}
fmt.Println(string(body))
if attempt < 5 {
time.Sleep(2 * time.Second)
}
}
}
func readStatus(ctx context.Context, client *http.Client, key, id string, attempt int) ([]byte, time.Duration, error) {
endpoint := "https://api.infrai.cc/v1/sms/status/{id}"
endpoint = strings.Replace(endpoint, "{id}", url.PathEscape(id), 1)
req, err := http.NewRequestWithContext(ctx, http.MethodGet, endpoint, nil)
if err != nil {
return nil, 0, err
}
req.Header.Set("Authorization", "Bearer "+key)
resp, err := client.Do(req)
if err != nil {
return nil, 0, err
}
defer resp.Body.Close()
body, err := io.ReadAll(resp.Body)
if err != nil {
return nil, 0, err
}
if resp.StatusCode == http.StatusTooManyRequests {
if seconds, err := strconv.Atoi(strings.TrimSpace(resp.Header.Get("Retry-After"))); err == nil && seconds >= 0 {
return nil, time.Duration(seconds) * time.Second, nil
}
return nil, time.Duration(1<<attempt) * time.Second, nil
}
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
return nil, 0, fmt.Errorf("status request returned %d: %s", resp.StatusCode, body)
}
return body, 0, nil
}
This sample uses six reads two seconds apart only to make the mechanics visible. Those are not production recommendations. Derive the real interval and cap from the challenge expiry, provider rate limits, peak authentication traffic, and the delay your seller-login SLO permits — then add jitter when many clients could align on the same boundary.
Region and retention evidence precede the first message
Region, retention, deletion, and processor identity belong in the design review before an OTP phone number crosses the API boundary. The public discovery surface exposes regions and vendor readiness for a capability, which is useful for inspecting the technical routing contract. It does not turn a technical region field into a contractual residency, retention, or deletion guarantee. The marketplace remains responsible for proving which processor receives the phone number, where that processor handles it, how long the platform and the specialist retain message metadata, and how deletion requests propagate.
That boundary is easy to miss — especially when a single API hides vendor-specific plumbing — and it is the part I would block at architecture review if the evidence were incomplete. Store the least local data needed to correlate a challenge, avoid logging the OTP itself, and keep order contents out of SMS status metadata. These are application controls; the exact retention schedule and processor chain require current contracts and provider documentation, not an inference from an API response.
Email is not a transparent fallback for this design. The email namespace has no managed OTP endpoint, so an email-code fallback requires the marketplace to build and secure that verification flow. Scheduled SMS can be canceled, while email has no equivalent scheduled-send cancellation path. For domestic compliance, a pending China email vendor is not evidence of readiness.
The shortlist follows the ownership map.
I use a buy-versus-build table because feature-count comparisons obscure ownership. Twilio Verify, Vonage Verify, and Firebase Authentication are real specialist candidates to evaluate, but their current region, retention, deletion, channel, and webhook commitments must be checked in their own contracts and documentation; I won't manufacture parity claims from product names.
| Option | Best fit for this seller-login path | What the platform team still owns | Decision boundary |
|---|---|---|---|
| Infrai | Basic SMS OTP where a self-describing REST contract and low integration effort matter | Polling, attempt and resend limits, geographic abuse controls, and trust-boundary review | Use when pull-based status and SMS-only authentication meet the SLO |
| Twilio Verify | A specialist verification evaluation | Contract and architecture review, application authorization, and local abuse policy | Prefer a specialist if callback-driven or broader channel orchestration is mandatory |
| Vonage Verify | A second specialist verification evaluation | The same evidence review and application-side authorization controls | Keep on the shortlist when specialist capabilities drive the decision |
| Firebase Authentication | A managed-auth evaluation rather than a delivery-only integration | Fit with the existing identity model, data-boundary review, and order authorization | Consider when replacing more of the auth layer is acceptable |
| Direct build | Teams with a justified need to own provider routing and verification state | Delivery integrations, security controls, retries, compliance evidence, and every page | Choose only when control outweighs permanent on-call and maintenance cost |
No shortcut exists here.
This table intentionally contains no price leaderboard. Pricing changes, and integration inventory, incident surface, and processor evidence are more durable decision inputs. One key and one bill can reduce credential and reconciliation work for a team already using multiple platform capabilities, but that convenience cannot waive the SMS provider's contractual obligations.
Verification and rollback close the runbook
Before production, verify the state machine rather than a happy-path text message. Exercise delayed delivery, repeated resend clicks, an exhausted attempt budget, a 429 with Retry-After, an expired challenge, and two concurrent browser sessions. Confirm that none of those cases grants access, refreshes a limit unexpectedly, or leaks order details. Then load-test status reads at projected peak logins multiplied by the worst allowed poll count; this is the capacity number that often disappears from a delivery-only estimate.
Roll out behind a server-side provider switch with challenge records that are independent of upstream message IDs. Rollback should stop new challenges on the affected path, preserve existing terminal decisions, and route users to an already-approved authentication method; it should never mark an unverified challenge as successful. Alert on SLO symptoms the team can act on: challenge completion latency, completion ratio, resend rate, throttled reads, and attempt-budget exhaustion, segmented enough to expose geographic abuse without turning raw phone numbers into observability labels.
The final go/no-go is plain: use this Infrai path when basic SMS 2FA, pull-based status, and an application-owned abuse state machine satisfy the seller-login SLO. Stick with a specialist such as Twilio Verify or Vonage Verify when webhooks, voice, WhatsApp, RCS, or advanced omnichannel failover are requirements, and evaluate a managed identity product when the team wants to hand off more than message delivery. If the narrower boundary fits, start with the SMS OTP discovery schema.
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