Sideline Checker: bulk Sideline verification, API & CSV output guide

Sideline Checker answers whether a contact is registered on Sideline. Bulk signal for CRM and marketing ops.

Sideline Checker (sideline) is Cheker.pro bulk Sideline verification. This guide covers mass phone checks, sideline API, phone intelligence, list hygiene before SMS/messengers, and CSV export for CRM.

Badge NEW in catalog.

Who it is for

Sideline Checker is used by SMS hubs, performance marketing, crypto compliance, call centers and SaaS with Reseller API. If your pipeline segments «has Sideline / not» — this task type covers bulk at scale.

What Sideline Checker does

Detect whether phone numbers are registered on Sideline. Each input line becomes one CSV row with result fields.

Task type: sideline. Family: Sideline. Input type: phone.

Pricing and output on Sideline Checker landing. Run tasks in dashboard.

Input file format

Upload TXT or CSV: phone numbers in international format (E.164 recommended, e.g. +14155552671). One file = one country only (country code in every line: Brazil 55, US 1, Russia 7).

• Minimum: 500 lines per task
• Maximum: 10,000,000 lines (large files auto-split)
• E.164 recommended: +country code, no spaces or brackets
• See format preview in the upload form at Sideline Checker

Do not mix phone, email and username in one file. From Excel export a single column to CSV — avoid formulas and scientific notation.

Output fields

• Number
• sideline: yes/no

Interpret Number · sideline: yes/no with a clear rule: «yes» → Sideline channel candidate; «no» → SMS/email fallback or exclude from campaign.

Use cases

• Marketing runs a separate sequence for "Sideline: yes".
• Marketing runs a separate sequence for "Sideline: yes".
• Marketing runs a separate sequence for "Sideline: yes".

How to run a check

1. Sign up at Cheker.pro and top up USDT
2. Open Sideline Checker — TXT/CSV upload form
3. Wait for completion in «Мои задачи»
4. Download CSV into CRM / SMS hub / BI
5. Automation: Reseller API — sideline

Common mistakes

• Local format without country code → false «no» results.
• Mixed countries in one file → API rejection or wrong output.
• Confusing Sideline registration with «number is reachable» — different signals.
• Treating «no» as permanent block without re-check after 7–14 days.
• Bulk-check without legal basis (GDPR / local telecom rules) — validation does not replace consent.

Reading yes/no

"No" on Sideline may mean no account, privacy settings, or upstream lag. Do not auto-block on one field alone.

FAQ

How is Sideline Checker different from other Sideline checkers?

Task type sideline: Detect whether phone numbers are registered on Sideline. Output: Number · sideline: yes/no. Compare family variants in the checker catalog and sideline landing.

Minimum batch size and file format for sideline?

Minimum 500 lines. phone numbers in international format (E.164 recommended, e.g. +14155552671). One country per file. Format hints on the upload page.

How much does Sideline Checker cost?

Pay-as-you-go USDT: per-line billing at checker rate. Current price per 10k lines on the sideline card and dashboard after top-up.

API for Sideline Checker?

Yes. Reseller API: POST /api/v1/check with task type sideline. Keys: API keys, docs: /docs.

Is bulk checking legal?

Use only lists with opt-in or other lawful basis (GDPR, local rules). Cheker.pro acts as processor on your instructions; you define retention and consent policy.

Summary: Sideline Checker is the bulk layer for Sideline. Catalog: sideline · run → · Cheker.pro blog