Application Numbers are the phone numbers or sender identities used by businesses or applications to send and receive SMS messages. These numbers act as sender IDs, helping recipients identify who the message is from and determining how replies are routed back to the business.
Application numbers can be numeric (like long codes or short codes) or alphanumeric (brand names), depending on the messaging requirements and country regulations. The format, capabilities, cost, and regulations of these numbers vary across countries and carriers.
Different Types of Phone Numbers #
-
Long Code Numbers or 10DLC #
Long codes are standard phone numbers (10–16 digits) used for voice and SMS. They support two-way messaging but are subject to throughput restrictions because they run on person-to-person (P2P) routes.
Key Characteristics #
- Typically 10–16 digits (varies by country)
- Supports two-way messaging
- Sending speed: ~1 message every 1–2 seconds
- Low cost compared to short codes
- Limited daily throughput to prevent carrier blocking
Country-Specific Notes #
- USA: Long codes must be registered as A2P 10DLC. Unregistered traffic gets blocked. Major carriers: AT&T, T-Mobile, Verizon.
- UK: Long codes (UK virtual mobiles) support two-way SMS freely. Providers: Vodafone UK, O2, EE.
- Australia: Long codes (virtual mobile numbers) are heavily used in two-way messaging. Providers: Telstra, Optus.
Common Providers Offering Long Codes #
- Twilio
- Vonage
- SendGrid
- MessageBird
2. Fixed-Line Numbers #
These are geographic landline numbers capable of receiving and sending SMS through carrier provisioning.
Key Features:
- Works well for businesses already promoting their landline.
- Popular in Europe, especially the UK & Germany.
- Requires SMS-enabled provisioning through providers like Twilio, BT (UK).
3. VoIP Numbers (Voice over Internet Protocol) #
A VoIP number is a virtual phone number that uses the internet to make and receive calls instead of traditional phone lines. They are virtual numbers using internet telephony systems.
Key Points:
- Assigned to a user, not a physical line.
- Supports SMS only if the carrier enables SMS routing.
- Works across devices such as laptops, IP phones, or mobile apps.
Typical VoIP providers:
- RingCentral
- Zoom Phone
- Google Voice
- 8×8
- Dialpad
Not all VoIP carriers allow SMS hosting- this varies by region.
4. Toll-Free Numbers #
Toll-free SMS numbers allow recipients to text or reply without charges.
Key Advantages:
- High deliverability in the US & Canada
- Allows two-way SMS messaging
- Less filtering compared to unregistered long codes
Country Notes:
- US/Canada: Most common. Requires toll-free verification for better deliverability.
- Australia & UK: Toll-free SMS use is very limited.
Providers:
- Twilio
- AVOXI
- Vonage
5. Short Codes #
Short codes are 4–8 digit high-throughput numbers designed for large-scale SMS campaigns.
Key Characteristics #
- Very high throughput (up to 200–500 SMS per second)
- Pre-approved by carriers → minimal spam filtering
- Expensive but best for large audiences
- Supports 1-way messaging
Country-Specific Examples #
- USA: 5–6 digit dedicated/shared codes; strict auditing by CTIA.
- UK: 5-digit short codes; managed by Phone-paid Services Authority (PSA).
- UAE/Saudi Arabia: Requires brand-level approval by telecom regulators.
Typical Providers for Short Codes #
- Vonage
- EZ Texting
- Twilio
6. Random Short Codes #
These are allocated automatically by the carrier or provider with no customization option.
7. Vanity Short Codes #
A business selects the specific number (e.g., “70000”). Ideal for branding and memorability.
8. FTEU (Free-To-End-User) #
Recipients can text the short code without any charges.
Most common in US & Canada, supported by providers like Infobip and Syniverse.
Custom Alphanumeric Sender IDs #
Alphanumeric IDs allow businesses to send SMS using a brand name instead of a phone number.
Key Features #
- Up to 11 characters
- Supports uppercase, lowercase, and numbers
- One-way only—recipients cannot reply
- Excellent for branding & recognition
Country Rules #
- Allowed: UK, UAE, Saudi Arabia, Singapore, Australia, most of Europe
- Restricted/Not Allowed: USA, Canada
Can I Bring My Own Number? (BYON) #
Businesses may use their existing fixed-line or VoIP number for SMS by hosting or porting it through an SMS provider.
Not allowed for: Mobile carrier numbers in certain regions (e.g., US mobile numbers).
Hosting (Enabling SMS on Your Existing Number) #
Hosting allows a business to enable SMS capability on an existing fixed-line or VoIP number without transferring the number away from the current carrier.
How It Works #
- The business keeps its current carrier for voice calls
- SMS capability is activated through a different SMS provider
- Incoming & outgoing SMS messages route through that SMS provider
Advantages #
- Keep the same number used in all marketing and customer communication
- No disruption to existing voice services
- Ideal for businesses locked in long-term carrier contracts
Limitations #
- Requires cooperation from both the SMS provider and the telephony carrier
- Higher cost because two vendors are involved
- Not feasible for mobile numbers in many countries
- Some VoIP carriers block SMS hosting entirely
Porting (Transferring Number for Full SMS & Calling Control) #
Porting transfers both the SMS and voice capabilities of a number to a new provider.
How It Works #
- The number is moved away from the current carrier
- The new provider manages both voice and SMS
- Business only pays one vendor for all telephony services
Advantages #
- Lower long-term cost
- Better control of messaging throughput and deliverability
- Simplifies management (single provider)
- Often enables richer routing, compliance handling, and reporting
Limitations #
- Porting timelines vary (US: ~2–10 days, EU: 3–15 days)
- Requires documents for number ownership
- Not allowed for mobile numbers in many regions
- Temporary downtime may occur depending on the carrier
Can I Bring My Own Carrier? (BYOC) #
Some businesses prefer to retain their existing carrier network especially large enterprises tied to long-term telecom contracts.
How BYOC Works #
- SMS originates from the app/platform but is delivered using the business’s existing carrier
- The carrier handles delivery, filtering, and routing
- The business’s telephony contract remains unchanged
Advantages #
- Full control over routing and SMS delivery
- Helpful for regulated industries or enterprises with strict telecom policies
- No need to change existing carrier contracts
Important Notes #
- Deliverability depends entirely on the carrier
- Some carriers have stricter filtering rules
- Not every carrier supports BYOC for business SMS
