Where Relayion Works Best
This page reflects current carrier behavior as we understand it. Questions? hello@relayion.com
How Relayion sends SMS
Relayion routes messages through a real Android device using a standard SIM card on the carrier's person-to-person (P2P) network, the same route used by a regular text message from a phone. This is different from commercial A2P (application-to-person) SMS, which goes through licensed aggregators with registered sender IDs.
This distinction matters because some carriers and regulators treat commercial content differently from personal messages, regardless of how it is sent. In certain markets, regulatory frameworks specifically require commercial SMS to flow through licensed channels and block everything else.
The good news: in many countries, conversational SMS, operational notifications, appointment reminders, and internal business messaging work well through Relayion. The sections below highlight the markets where additional carrier or regulatory restrictions apply.
Generally supported markets
Relayion works well in markets where carriers primarily focus on spam detection rather than mandatory commercial SMS routing. Normal conversational traffic and moderate-volume operational messaging are generally suitable in these regions.
- United States
- Canada
- United Kingdom
- Australia
- New Zealand
This is not an exhaustive list, and carrier behavior can change. If you are unsure about your target market, reach us at hello@relayion.com.
Markets with hard restrictions
In these markets, carrier-level enforcement is consistent and not content-dependent. Messages will be blocked regardless of volume, tone, or template.
India (+91)
Indian carriers enforce TRAI's DLT (Distributed Ledger Technology) regulation, which requires all commercial SMS (including OTPs, transactional messages, and promotional content) to be sent through licensed aggregators with pre-registered sender IDs and message templates. Messages that match commercial patterns sent via P2P SIMs are blocked at the carrier network level before delivery. This is consistent enforcement, not an intermittent issue. Relayion cannot reliably deliver OTPs or commercial content to Indian numbers.
Philippines (+63)
Philippine carriers (Globe, Smart, DITO) prohibit P2P traffic for commercial purposes. Additionally, the Bangko Sentral ng Pilipinas (BSP) requires all banks to move away from SMS OTP under AFASA. Relayion is generally not suitable for commercial messaging targeting Philippine mobile networks due to carrier policies and regulatory requirements.
Markets with partial restrictions
In these markets, filtering is content-dependent rather than a blanket block. Conversational messages at moderate volume are generally unaffected. Commercial or OTP-style content is more likely to be filtered.
Malaysia
The MCMC prohibits all SMS from including hyperlinks, requests for personal data, or callback numbers. Messages containing these will be blocked or filtered. Conversational notifications without links or data requests should work.
Indonesia
Kominfo oversees sender ID registration for commercial content. Messages that pattern-match commercial or OTP content may be filtered. Conversational use cases are generally unaffected.
Thailand
AIS and other carriers apply pattern-based filtering. Repeated sends of similar content (especially OTP-style messages) from the same SIM will trigger detection. Low-volume, varied conversational messages are less likely to be affected.
Vietnam
Viettel and Vinaphone filter repeated numeric senders and flag high-frequency similar-content traffic. The same consideration as Thailand applies.
Universal carrier limitations
These limitations apply in all markets, regardless of geography.
- Daily volume caps. Carriers silently cap how many SMS a single SIM can send per day. Thresholds vary by carrier but typically fall between 100 and 300 messages. Exceeding this may result in temporary SIM throttling or blocking.
- Content pattern detection. Template-like content such as "Your OTP is...", "Verification Code:", or "Click here to confirm" triggers commercial content filters even in markets without explicit regulation.
- Burst sending. Sending a large number of messages in a short window raises SIM box detection flags across most carrier networks globally.
- International recipients. A SIM registered in one country sending to numbers in another is routed differently and may face additional carrier scrutiny.
What Relayion is best suited for
- Internal team notifications
- Appointment reminders
- Operational alerts
- Personal automation at low volume with conversational tone
If your use case is conversational, operational, or device-based messaging, Relayion is designed for exactly that. If you need guaranteed commercial SMS delivery at scale in regulated markets, a licensed A2P provider is the better choice.