Before Your First 10DLC Text Campaign: Preparing the Phone List
Before your first 10DLC text campaign, make sure every number on the list has a consent record, is formatted in E.164, appears only once, is not on your opt-out list, and has been checked for line type so you are not texting landlines. Brand and campaign registration gets your traffic accepted by carriers; list preparation keeps failed messages and complaints down.
This is a practical checklist, not legal advice. Messaging rules change, so check your provider's current requirements and get legal advice where needed.
Step 1: Confirm consent for every number
Carrier policies and US law require consent for marketing texts, and campaign registration asks how you collect it.
| Keep | Why |
|---|---|
| Date and time of opt-in | Shows when consent was given |
| Where it happened (form, keyword, checkout) | Matches the opt-in method in your campaign registration |
| The wording they agreed to | Shows what they were told they would receive |
| The number as entered | Ties consent to the exact number |
Numbers without a consent record do not belong in a marketing campaign, however clean they are. TCPA: mobile vs landline covers why line type matters legally too.
Step 2: Remove opt-outs
Subtract everyone who has replied STOP or otherwise opted out, from any campaign or number you have used. Keep a single master opt-out list and check every upload against it. The SMS compliance message generator helps write opt-in confirmations and opt-out wording.
Step 3: Format to E.164
Messaging providers expect numbers like +14155550123. Lists from forms and CRMs contain every format imaginable: brackets, dashes, missing country codes, leading 1s and extensions.
- Normalise with the phone number formatter.
- Flag rows that cannot be parsed and fix them by hand or remove them.
E.164 phone number format explains the rules.
Step 4: Dedupe after formatting
The same person often appears as "(415) 555-0123" and "+1 415 555 0123". Dedupe only after formatting, using the duplicate phone number remover, so they collapse into one row. Otherwise the same person gets two texts.
Step 5: Check line type
Most standard landlines cannot receive SMS, so texting them wastes money and adds failures. In the US and Canada, mobile and landline numbers share the same ranges, so line type needs a lookup against carrier data rather than a guess from the number.
| Line type | Usual handling for SMS |
|---|---|
| Mobile | Keep |
| Landline | Remove from the SMS list or review |
| VoIP | Review; some accept texts, some do not |
| Toll-free | Usually remove from a 10DLC list |
| Unknown | Review before sending |
The free landline or mobile checker handles single numbers. For full lists, SimpleVerifier offers live carrier lookups for line type and carrier as a paid extra; see pricing.
Step 6: Consider reassigned numbers
Numbers get disconnected and reassigned to new people. If your consent records are old, the person who opted in may no longer have the number. The FCC's Reassigned Numbers Database exists for this; see our guide to it.
Step 7: Send a small batch first
Start with a small, recent, engaged segment. Watch the delivery report and error codes before sending to everyone. Twilio SMS error codes 30003 to 30008 and why SMS delivery fails explain common failures.
Keep messages within one segment
Long messages and special characters split texts into multiple billable parts. Check your copy with the SMS character counter and estimate spend with the SMS cost calculator. GSM-7 vs UCS-2 explains why one emoji can double the cost.
What validation cannot do
| Validation can | Validation cannot |
|---|---|
| Fix formatting and find malformed numbers | Confirm the number is in service |
| Identify the registered line type | Confirm the number can receive SMS |
| Remove duplicates | Prove consent |
| Show the carrier on a live lookup | Tell you who currently holds the number |
Pre-send checklist
- Consent record for every number
- Opt-outs removed against the master list
- All numbers in E.164
- Deduped after formatting
- Line type checked; landlines removed or reviewed
- Old consent checked for reassigned numbers
- Small test batch sent and reviewed
Keep the list clean over time
Re-run formatting and line-type checks on new numbers as they arrive, and process opt-outs immediately. A list that is cleaned once before launch and never again drifts back to where it started.
Clean your list
The free bulk phone number validator handles formatting and validity checks. If you also have email addresses for these contacts, you get 100 free email checks when you sign in with Google, no card, on the verify page.
Common questions
What is 10DLC?
10DLC stands for 10-digit long code: a standard US phone number used for application-to-person (A2P) texting. US carriers require businesses sending A2P texts on these numbers to register a brand and campaign through their messaging provider.
Do I need consent to send a 10DLC marketing text?
US rules and carrier policies require consent for marketing texts, and campaign registration asks how you collect it. Keep records of when and how each person opted in. Get legal advice for your specific situation.
Should I remove landlines from an SMS list?
Most standard landlines cannot receive SMS, so messages to them are usually wasted and can count against delivery metrics. A line-type check identifies numbers registered as landlines so you can remove or review them.
Can phone validation tell me a number will receive my text?
No. Format and line-type checks tell you a number is correctly structured and what type of line it is registered as. They cannot confirm the number is in service or able to receive texts.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.