PolyAI uses Twilio as the underlying SMS provider. The availability data, throughput figures, and regulation links below come from Twilio’s published guidelines.
Number types
There are two main types of SMS-capable phone number. Choosing between them depends on your expected message volume and how quickly you need to go live. MPS (messages per second) is the maximum rate at which a number can send SMS. Higher MPS means you can handle more concurrent conversations without queuing delays.| Type | Best for | Throughput (MPS) | Typical lead time |
|---|---|---|---|
| Short code (5–6 digits) | High-volume transactional messaging. Highest throughput and best carrier deliverability. | 1,000–3,000 (US/CA) | 6–16 weeks (carrier approval required) |
| Long code (standard phone number format) | Conversational 2-way SMS, moderate volume. | 10–225 depending on country | Immediate to several weeks |
Availability by country
“Private Offering” means the number type is available but requires a direct arrangement with Twilio — contact your Twilio account manager to set it up.North America
| Country | 2-way SMS | Short code | SC MPS | SC lead time | Long code | LC MPS | LC lead time | Regulations |
|---|---|---|---|---|---|---|---|---|
| United States | Yes | Available | 1,000–3,000 | 6–10 weeks | Available | 225 (75 per major carrier) | Immediate | US SMS guidelines |
| Canada | Yes | Available | 1,000–3,000 | 6–10 weeks | Available | 225 (75 per major carrier) | Immediate | CA SMS guidelines |
Europe — 2-way SMS supported
| Country | Short code | SC MPS | SC lead time | Long code | LC MPS | LC lead time | Regulations |
|---|---|---|---|---|---|---|---|
| United Kingdom | Available | 300+ | 10–16 weeks | Available | 10 | Immediate | UK guidelines |
| Germany | Available | — | Private Offering | Available | 10 | Immediate | DE guidelines |
| France | Available | — | Private Offering | Available | 10 | Private Offering | FR guidelines |
| Ireland | Not available | — | — | Available | 10 | — | IE guidelines |
| Netherlands | Not available | — | — | Available | 10 | Immediate | NL guidelines |
| Italy | Not available | — | — | Available | 10 | Private Offering | IT guidelines |
| Czech Republic | Not available | — | — | Available | 10 | Immediate | CZ guidelines |
Europe — 2-way SMS not supported
These countries do not currently support 2-way SMS through Twilio. Neither short codes nor long codes are available for bidirectional messaging.| Country | Regulations |
|---|---|
| Croatia | HR guidelines |
| Bulgaria | BG guidelines |
| Slovakia | SK guidelines |
Compliance requirements
Carrier regulations vary by country and must be met before you send any messages. Non-compliance can result in messages being silently dropped or your number being suspended.US and Canada — A2P 10DLC
US and Canadian long code SMS requires A2P 10DLC registration. Without it, carriers block messages entirely. See the SMS overview for the full registration walkthrough. For short code campaigns:- US: Follow the CTIA Short Code Monitoring Handbook and Messaging Principles and Best Practices.
- Canada: Follow the Canadian Wireless Telecommunications Association (txt.ca) guidelines.
- Both US and CA short code applications require a screenshot or mock-up of the opt-in process.
United Kingdom
- Follow the UK Mobile Network Operator Code of Practice.
- Short code provisioning takes 10–16 weeks and goes through a separate carrier approval process.
- Long codes are available immediately through the Twilio Console.
EU countries
Each EU country has its own regulatory framework — check the regulation links in the tables above. Key considerations:- Some countries (France, Italy) require a Private Offering arrangement with Twilio for number provisioning.
- GDPR applies to all EU SMS communications — ensure you have appropriate consent and opt-out mechanisms.
Pre-launch checklist
Before going live with 2-way SMS in any country:- Confirm number availability — check the tables above to verify your target country supports 2-way SMS and that the number type you need is available.
- Provision your number — long codes can often be provisioned immediately through the Twilio Console; short codes require a carrier application.
- Complete registration — for US/CA, complete A2P 10DLC registration. For other countries, follow the linked regulatory guidelines.
- Validate your campaign — use the A2P Campaign Pre-Scanner to check your setup against carrier requirements before sending.
- Connect to PolyAI — follow the SMS setup guide to link your Twilio number to your PolyAI project.
Industry resources
Regulatory bodies
- CTIA — The Wireless Association — US industry body governing short code campaigns and A2P messaging standards.
- Canadian Wireless Telecommunications Association (CWTA / txt.ca) — Canadian equivalent; governs short code applications and carrier compliance.
- Ofcom — Premium Rate Services — UK regulator for premium-rate and short code services (took over from the PSA in 2025).
- BEREC — Body of European Regulators for Electronic Communications — EU-wide telecom regulatory coordination.
Twilio documentation
- Twilio Messaging Guidelines by Country — per-country SMS regulations, sender types, and carrier requirements.
- A2P 10DLC Overview — registration walkthrough for US and Canadian long code SMS.
- Twilio Short Code Guide — how short codes work, provisioning, and compliance requirements.
- Twilio Short Code Provisioning in Console — step-by-step application walkthrough.
- Twilio Messaging Services — number pooling, compliance, and scaling for high-volume use cases.
- Twilio Phone Number Regulatory Compliance — identity and address verification requirements by country.
Carrier compliance
- CTIA Short Code Monitoring Handbook (v1.9, PDF) — rules for US short code campaigns.
- CTIA Messaging Principles and Best Practices (May 2023, PDF) — US carrier expectations for A2P messaging content and opt-in.
- UK Code of Practice for Common Short Codes — UK MNO requirements for short code services.
Compliance tools
- A2P Campaign Pre-Scanner — validate your campaign setup against carrier requirements before launch.
- Twilio Trust Hub — manage brand and campaign registrations for A2P compliance.
Related pages
SMS overview
Set up Twilio, create templates, and send SMS from your agent.
Twilio integration
Connect your Twilio account for voice and SMS.
Buy a number from PolyAI
Purchase PolyAI-provisioned numbers for voice.