46 articles.
Guides
Cambodia phone number format: +855 and 8- or 9-digit mobiles, TRC prefixes for Cellcard, Smart, Metfone and Seatel, tested code, SIM rules and Telegram checks.
19 min read
Guides
Kuwait phone number format: +965 plus 8 digits, mobiles on 41, 5, 6 and 9, tested code for library gaps, porting since 2013 and the new 2025 MNP rules.
21 min read
Guides
Qatar phone number format: +974 plus 8 digits, mobiles on 3, 5, 6 and 7, tested validation code, porting since 2013, sender rules and PDPPL consent.
21 min read
Guides
Tanzania phone number format: +255 and 9-digit 06/07 mobiles, TCRA operator prefixes (Vodacom, Yas, Airtel, Halotel, TTCL), tested code, porting and SMS rules.
20 min read
Guides
Dutch phone number format: +31 plus 9 digits, 06 mobiles, 0970 M2M numbers, tested validation code, 1-day porting, opt-in sales calls and SMS consent.
19 min read
Research
WhatsApp authentication rates for 44 markets (Meta, October 2026), why SMS OTP prices differ by country, and when a number check costs less than a wasted code.
14 min read
Guides
Polish phone number format: +48 plus 9 digits, no trunk 0, 13 mobile prefixes, tested validation code, 1-day porting, anti-spoofing law and SMS consent.
19 min read
Guides
Taiwan phone number format: +886 and 10-digit 09 mobiles, area codes, 0800 and 070 ranges, tested code, porting since 2005 and the anti-fraud SMS rules.
24 min read
Guides
Indonesian numbers: the +62 format, why mobiles have 9 to 12 digits, the 08XX prefixes, tested validation code, no mobile porting, and Komdigi's 2026 SIM registration rules.
11 min read
Guides
French phone number format: +33 plus 9 digits, 06/07 mobiles, Arcep prefixes, tested validation code, RIO porting, opt-in sales calls and SMS consent.
24 min read
Guides
India phone number format: +91 plus 10 digits, mobile prefixes 6-9, tested validation code, porting (MNP) rules, DLT sender rules and the 140/1600 series.
18 min read
Guides
Italian phone number format: +39, 3xx mobiles with 9 or 10 digits, landlines that keep the 0, tested validation code, porting, the RPO and anti-spoofing.
22 min read
Guides
Japanese phone number format: +81 and 11-digit 070/080/090 mobiles, 050, 020 and 0120 ranges, tested code, one-stop porting and opt-in SMS rules.
22 min read
Guides
Nigerian numbers: the +234 format, the 070, 080, 081, 090 and 091 mobile prefixes, tested validation code, 48-hour porting, NCC's DND 2442 and NIN-SIM rules.
12 min read
Guides
South Korean phone number format: +82 and 11-digit 010 mobiles, area codes, 070 and 1588 numbers, tested code, porting and the ad-label SMS rules.
22 min read
Guides
Spanish phone number format: +34 plus 9 digits, 6/7 mobiles, 8/9 landlines, tested validation code, 1-day porting, 400 numbers for sales calls and SMS rules.
20 min read
Guides
Australian phone number format: +61, 10-digit 04 mobiles, area codes, tested validation code, porting since 2001 and the SMS Sender ID Register.
17 min read
Guides
Colombia phone number format: +57 and 10-digit 3XX mobiles, the 2021 60X landline change, tested code, porting, Ley 2300 contact hours and WhatsApp checks.
19 min read
Guides
German phone number format: +49, variable-length numbers, 015/016/017 mobile prefixes, tested validation code, porting since 2002 and UWG consent rules.
18 min read
Guides
Kenya phone number format: +254 and 9-digit 07/01 mobiles, the CA's operator prefixes, tested code, 4-hour porting, SIM registration and SMS marketing rules.
19 min read
Guides
Nepal phone number format: +977 and 10-digit 9XX mobiles, NTC and Ncell prefixes, tested code, why porting isn't live yet, and NTA's SMS and privacy rules.
18 min read
Guides
US phone number format: +1 plus 10 digits (NPA-NXX-XXXX), US vs Canada area codes, tested validation code, porting, 10DLC, TCPA and the FCC reassigned database.
18 min read
Guides
Pakistani numbers: the +92 format, which 03XX codes are mobile, tested validation code, porting, PTA's short-code and consent rules, and the 3627 register.
11 min read
Guides
What TRAI's TCCCPR Third Amendment of 18 September 2026 changes: AI spam flagging, A2P call declaration, 6-hour header suspension, 7-day inquiry consent, 140/1600/1601.
9 min read
Guides
What the TCPA revoke-all opt-out rule required, why it was delayed to 31 January 2027, how the FCC's September 2026 order (FCC 26-67) replaces it, and an opt-out data model. Not legal advice.
11 min read
Deliverability
How US 10DLC registration works: brands, campaigns, timelines, published fees, throughput, why registered messages still get blocked, and list hygiene.
7 min read
Guides
Thailand phone number format: +66 and 10-digit mobiles (06, 08, 09), the 0066 parsing trap, tested code, porting, SIM identity rules and LINE checks.
17 min read
Deliverability
What direct-to-carrier A2P SMS really means, how it differs from aggregator, grey and SIM farm routes, and six tests to check whether your route is direct.
13 min read
Deliverability
Why a number is not SMS-capable (landline, toll-free, VoIP, invalid, opted out), what the API error codes mean, and how to check a number before you send.
14 min read
Guides
Sri Lankan mobiles are +94 plus 9 digits starting with 7 (07X at home). Operators by prefix, tested code, porting status, SMS rules and PDPA dates.
14 min read
Guides
Vietnamese mobiles are +84 plus 9 digits (10 with the leading 0) since the 2018 switch from 11 digits. Prefixes, tested code, porting and anti-spam rules.
17 min read
Guides
Bangladeshi mobiles are +880 plus 10 digits starting 1 (01X at home: 011, 013-019). Since porting began in 2018, the prefix no longer proves the network.
13 min read
Guides
Malaysian mobiles are +60 1X plus 7 digits, or +60 11 plus 8, so a fixed 10-digit rule rejects valid 011 numbers. Prefixes, tested code, porting, MCMC rules.
14 min read
Deliverability
How to check if a number has Viber, where Viber matters most, how checks relate to Viber Business Messages, and a cost model for Viber-first sending.
7 min read
Guides
Hong Kong phone number format: +852 and 8 digits, no area codes or trunk 0, which first digits are mobile, tested validation code, porting and SIM rules.
13 min read
Guides
Macau phone number format: +853 and 8 digits with no area codes, mobiles in the 62, 63, 65, 66 and 68 blocks, tested validation code and the Hong Kong overlap.
13 min read
Guides
A dated TCPA checklist for SMS: consent, opt-out words, 10-day revocation, quiet hours, do-not-call, reassigned numbers and list hygiene. Not legal advice.
9 min read
Deliverability
A2P SMS is text messaging sent by software for a business. How it differs from P2P, sender types, what drives cost, deliverability and SMS pumping risk.
8 min read
Deliverability
What an SMS delivery report is, what DELIVRD, UNDELIV, EXPIRED and REJECTD mean, why 'delivered' isn't proof of reading, and why DLRs go missing or wrong.
7 min read
Deliverability
RCS (Rich Communication Services) upgrades SMS in the default messaging app. What the spec covers, RCS vs SMS and chat apps, and how to check who can get it.
7 min read
Guides
Absent subscriber: the number exists but the phone is off or out of reach. Unknown subscriber: the number is not assigned. Each HLR result and what to do next.
10 min read
Deliverability
WhatsApp, Telegram, Viber, LINE, Zalo, RCS or SMS? How to pick a channel per country for messages customers expect, and measure it on your own base.
7 min read
Deliverability
To test if a number supports RCS, run a capability check: capable, not capable or unknown, before you send. Plus test numbers, iPhone support and SMS fallback.
9 min read
Deliverability
WhatsApp OTP pricing in 2026: Meta charges $0.0008 to $0.0550 per delivered authentication message, by country. Rates vs SMS and a cost-per-user calculator.
9 min read
Deliverability
A delivery receipt reports what happened after you sent an SMS. An HLR lookup asks the network before you send. What each can see, miss and cost.
7 min read
Deliverability
A cause tree for undelivered SMS: invalid numbers, unreachable phones, wrong line types, carrier filtering and handsets, with a fix for each.
7 min read
