Specified Transfer Listing Service (STLS)


The Specified Transfer Listing Service (STLS) is an optional service that helps connect organizations seeking to acquire IPv4 address space, organizations looking to transfer unused IPv4 address space, and parties interested in facilitating the transfer process. The STLS is specifically for Transfers between Specified Recipients within the ARIN Region (Number Resource Policy Manual (NRPM) 8.3) and Inter-RIR Transfers (NRPM 8.4).

The STLS is only for those organizations wishing to obtain IPv4 address space from another organization. If you wish to request IPv4 space directly from ARIN, please refer to the ARIN IPv4 Waiting List page for your options.

This service is provided as a courtesy by ARIN, but organizations are not required to use STLS when transferring IPv4 address space. If you are ready to request a transfer (for example, if you are a recipient and already know the source of the IPv4 address space you wish to acquire), you may submit a transfer request without registering to use the STLS.

Why Use the STLS?

The STLS may be a helpful option for:

  • Organizations in need of IPv4 address space but unsure of where to get it (Recipients)
    • Recipients use the STLS to access a list of organizations with IPv4 address space that have been validated and are available for transfer.
  • Organizations with unused IPv4 address space unsure of the organization to whom they wish to transfer it (Sources)
    • Sources use the STLS to access a list of organizations that have been pre-approved to receive IPv4 address space, list their own space as available for transfer, or find a transfer facilitator.
  • Parties looking to facilitate a transfer between two organizations (Facilitators)

Looking for Facilitators to assist with your transfer? Visit our Registered Transfer Facilitators page.

Public STLS Summary Report

ARIN publishes a Public STLS Summary Report that includes:

  • IPv4 address block sizes listed as available
  • IPv4 address block sizes listed as needed
  • Current number of Transfer Facilitators

The report does not contain any organizational name or contact information; those are available only to registered STLS participants.


Note: Organizations that want to list a need for IPv4 addresses through the STLS must have established Point of Contact (POC) handle(s) and an Organization Identifier (Org ID) with ARIN. These must be linked to an ARIN Online account. For additional information, visit Resource Requests: Getting Started.

Before participating in ARIN’s STLS as a recipient or source, please review ARIN’s Resource Transfer guidelines and Section 8 of the NRPM to ensure your organization and the IPv4 address space in question qualify for a resource transfer.

ARIN Registration Services vets all STLS participants, and requires adequate documentation to ensure the right to transfer. All STLS participants must be current on all ARIN payments. Requests to receive/transfer/facilitate the transfer of IPv4 addresses through the STLS are subject to the STLS Terms of Service, as well as the same policy criteria as requests submitted directly to ARIN.

IPv4 blocks listed as part of this service must be covered under a Registration Services Agreement (RSA) or Legacy Registration Services Agreement (LRSA) with ARIN.

Requesting STLS Participation

  1. Log in to your ARIN Online account.
  2. From the navigation menu, select Downloads & Services.
  3. In the Specified Transfer Listing Service (STLS) section, choose Request Participation in STLS.
  4. Read and accept the STLS Terms of Service Agreement shown in the window.
  5. Select how your organization wants to participate in the STLS, and follow the instructions to provide information about your organization, resources (if applicable), and contact information.
  6. After you choose Submit, the system creates a ticket for your request.

ARIN will verify your participation request within two business days and will send a notification to you in ARIN Online. If ARIN needs more information, we will request that via another notification. Note that a request for additional information does not imply a denied request.

Note: Each response cycle will generally take two business days. If ARIN does not receive a response within 90 days, the associated ticket will be closed.

For questions about pending requests, send a reply to the ticket through ARIN Online, or call ARIN’s Registration Services Help Desk at +1.703.227.0660. Please have the following available when you call:

  • Your ticket number
  • Access to www.arin.net and ARIN Online
  • Any requested documentation
  • The name of the Customer Service Resource Analyst who assisted you previously, if applicable

Additional guidance on calling the Help Desk is available.

STLS Participation Approval

Upon approval, ARIN will send you a notification in ARIN Online. This approval requires a response to verify your participation, and is valid for 90 days. If no response to the approval notification is received within 90 days, your request will need to be resubmitted.

Note: STLS recipients must provide an Officer Attestation certifying the accuracy of the request data prior to final approval.

Please contact Registration Services with any questions by replying to the ticket in ARIN Online, or calling ARIN’s Registration Services Help Desk at +1.703.227.0660


ARIN charges fees for STLS participation to offset the cost of its operation. Up-to-date fee information is provided in the fee schedule. Additional fees will apply for approved transfers and for recurring registration of transferred IPv4 address space. For information on how to make a payment, please visit the Make a Payment page.

STLS Access and STLS Report Retrieval

ARIN will provide STLS access to approved participants within two business days of receiving the listing fee. STLS participants have access to the STLS Report, which provides contact information for all registered recipients, sources, and facilitators. To download this report:

  1. Log in to ARIN Online.
  2. Choose Downloads & Services from the navigation menu. In the Specified Transfer Listing Service (STLS) section, the file is provided, along with a timestamp that shows the date and time that the file was last updated.

What’s Next?

Participants should contact either a registered facilitator or each other directly to arrange a transfer. Once two participants agree on a transfer, both parties should submit the appropriate transfer request. Visit the Transfers page for detailed instructions for Transfers between Specified Recipients within the ARIN Region (NRPM 8.3) and Inter-RIR Transfers (NRPM 8.4).

The STLS will operate indefinitely as long as adequate demand exists. ARIN reserves the right to modify or discontinue the service with appropriate advanced notice to participating parties.

Removal from STLS

Upon completion of a transfer between STLS participants, both involved parties will have their STLS listings and access removed upon completion of a transfer unless they have additional resources still listed. Subsequent STLS access will require resubmitting an STLS participation request.

Requesting an Additional Listing

If you are already an STLS participant, you can request an additional listing using ARIN Online. For example, if you are participating as a source, but can also participate as a recipient, you can request that additional listing. To request an additional listing:

  1. Log in to ARIN Online.
  2. Choose Downloads & Services from the navigation menu. In the Specified Transfer Listing Service (STLS) section, choose the additional way that your organization wants to participate in the STLS, and follow the instructions.
  3. After you choose Submit, the system creates a ticket for your request. Your request is processed following the guidelines discussed in Requesting STLS Participation.

Updating Your STLS Contact Information Listing

If you are a registered participant of the STLS (recipient, source, or facilitator) and need to update the contact information for your organization, you may do so by submitting an Ask ARIN request from within your ARIN Online account.

  1. Log in to your ARIN Online account.
  2. Select Ask ARIN from the navigation menu.
  3. Select Other from the list of topics.
  4. In the Subject field, enter Change STLS Information.
  5. Provide the following information in the Question field:
  • Organization Identifier (Org ID)
  • Organization Name
  • New Contact Name
  • New Contact Email
  • New Contact Phone number
  1. Submit the request.