Sub ID Central


Jessica Murray


T-Mobile has implemented a limit of 49 numbers per campaign in an effort to combat snowshoeing and ensure brands and campaigns are registered as intended (see note about ISVs below). If more than 49 telephone numbers (TNs) are legitimately required on one campaign, a Number Pool or Sub ID must be assigned to the campaign.

Note: ISVs are customers that support many brands (e.g., an ISV can support 100s of dental offices). All of the individual brands the ISV supports are required to be registered individually on their own campaign, as opposed to creating a Number Pool.

What is a Sub ID?

  • Sub IDs are Number Pool ranges that T-Mobile has preassigned to Bandwidth – the terms Number Pool and Sub ID can be used interchangeably, but the process of applying and assigning for each is different.
  • You must have campaigns registered in order for Bandwidth to assign a Sub ID to the campaign.
  • You can request a Sub ID ahead of registration, but we can't functionally assign a Sub ID without the campaigns.
  • You can assign TNs to a campaign before your Sub ID request is approved, but you'll have to reduce the TN quantity if it's not approved.
  • Number Pools and Sub IDs are for T-Mobile only. AT&T only has a limit of 5,000 TNs per campaign for Class N, insurance agents, franchises, and banks.

The following use cases will typically be approved for a Sub ID at Bandwidth's discretion, but it's not guaranteed. Please note that you're still required to register your brands and campaigns appropriately.

  • Group Messaging
  • Proxy (conversational) – typically this is where the numbers are rotated through a Number Pool (this doesn't apply when numbers are assigned to individuals)
  • Use cases that require locality (multiple offices/locations):
    • Franchises, banks, insurance agencies
    • Agents with dedicated phone numbers
    • Customer care
      • Hotels, hospitality, restaurants
      • Offices (doctors, dentists, etc.)
      • Contact centers
    • Churches
    • Emergency services (PSAP support)
    • Educational (multiple universities/schools)

If you have one of the use cases listed above or don't fall into any of the approved use cases but still have a legitimate need for >50 TNs per campaign, please fill out this form and we'll be in touch. Please note that Sub ID responses can take up to two weeks, but you can follow our Sub ID best practices to have the most successful and quickest Sub ID processing.

Important: Checking the box for Number Pooling in TCR or Bandwidth's portal DOES NOT constitute a Sub ID approval. The application must still be submitted and approved by Bandwidth.

Sub ID best practices

Providing detailed form responses will give Bandwidth a better picture of your traffic and help process your request in a timely fashion. We also advise providing detailed campaign descriptions and sample content, as this is what the carriers will be reviewing if there's ever an issue with your campaign.

Specify your use case(s)

This should mirror the campaign type from your campaign registration. If the campaign is Mixed Use, please identify all appropriate use case categories, not just one. 

👎 Not recommended: "Mixed: “Account Notifications”."

👍 Recommended: “Mixed: Account Notifications, 2FA, Customer Care, Marketing.”

Explain how opt-in is collected

List the steps a consumer takes to agree to receive SMS messages for this campaign, and provide a screenshot of the opt-in method, copy of a flier with a keyword, or any other proof of opt-in used.

👎 Not recommended: "Consumer can opt-in via SMS"

👍 Recommended: “Consumer can opt-in to receive SMS messages by texting SUBSCRIBE. They also have the option to text HELP for help or STOP to opt-out afterward."

Explain why you need more than 50 numbers

We need a clear picture of why more than 49 numbers are needed for a single campaign.

👎 Not recommended: “More than 50 Agents/locations” 

 👍 Recommended: “We have 50 agents working on a personal basis with the customers, who expect that number to be associated with their agent.”

Explain how the phone numbers are assigned

Provide as much detail as possible so it can be confirmed as a valid assignment (e.g., one number per agent, one number per store location, etc.)

👎 Not recommended: "Each employee has their own phone line."

👍 Recommended: We have 25 locations in the US and each employee (~100 employees per location) has a dedicated line."

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