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Nov 28
PSTN PRI to SIP or SIP Relocation
Posted by Freddy Tabet

In the dynamic landscape of modern telecommunications, the role of a Collaboration Engineer is one filled with continuous evolution and challenges. Throughout the course of their career, these professionals often find themselves at the forefront of critical transitions within an organization's communication infrastructure. One such pivotal juncture involves PSTN (Public Switched Telephone Network) cutovers, where the shift from traditional PRI (Primary Rate Interface) to SIP (Session Initiation Protocol) or the relocation of SIP services to new locations becomes imperative. These transitions represent not only an advancement in technology but also a profound transformation in how businesses communicate. To navigate these changes successfully, collaboration engineers must be ever-ready and meticulously attentive to ensure that every facet of the transition is thoughtfully considered and seamlessly executed. In this era of digital connectivity, being prepared for PSTN cutover scenarios is paramount to maintaining the flow of communication and upholding business continuity.

Integrating with a PSTN network represents a multifaceted challenge that requires not only technical prowess but also adept coordination skills. Collaboration Engineers often find themselves in the unique position of bridging different technologies and teams, ensuring that the transition from PRI to SIP, or any relocation of SIP services, occurs seamlessly. The primary goal of such integration efforts is to enhance communication efficiency and reduce costs, while simultaneously providing flexibility for future growth. However, achieving these objectives demands meticulous planning, rigorous testing, and precise execution. In this blog, we will delve into the crucial aspects that need to be thoroughly prepared to ensure a successful PSTN cutover or SIP relocation, emphasizing the key steps, tests, and considerations that Collaboration Engineers must undertake to facilitate a smooth transition.

Below are the steps to prepare for a successful cutover:

    1. Gather Circuit and Customer Information:
      Obtain pertinent details such as Circuit ID, customer name, and addressing information to establish a clear foundation for the transition.

  1. Identify Porting Numbers:
    Collaborate with the current PSTN provider to compile a comprehensive list of all associated numbers. Verify the necessity of each number with the customer to optimize resources.

  2. Device and Service Inventory:
    Ascertain the devices reliant on the ported numbers, with a focus on critical endpoints encompassing phones, fax machines, paging systems, fire alarms, and elevator phones.

  3. Connection Methodology:
    Determine the method of connecting to the PSTN provider, including considerations for on-site hardware deployment, internet-based connections, and any firewall traversal requirements.

  4. Schedule Cutover Date:
    Coordinate with the provider to establish a cutover date weeks in advance. Collaboratively select the optimal cutover window that minimizes disruption, acknowledging the possibility of unexpected issues.

  5. IP Addressing Scheme:
    Obtain crucial IP addressing information from the provider, specifying SIP call destinations, signaling, and media traffic IPs, as well as port details, such as 5060 for signaling and the media traffic range (16384 to 32676).

  6. Network Security Configuration:
    Collaborate with network security experts to secure the network, configure firewalls or access lists to safeguard against potential threats.

  7. Digit Configuration:
    Confirm with the new provider the expected number of digits for incoming and outgoing calls, including discussions with customers regarding dialing habits and caller ID preferences.

  8. Codec and Early Offer Settings:
    Define the codec to be employed and determine whether early offer functionality is enforced as part of the configuration.

  9. Local Device Configuration:
    Configure local devices, including voice service VoIP settings, trusted IPv4 subnets, SIP bindings, early offer configurations, voice translations, SIP profiles, and URI matching for incoming calls on Dial-peers.

  10. On-Demand Voice Turn Up:
    Collaborate with the provider to establish an on-demand voice turn-up, allowing for testing of key communication aspects, including phone systems, fax machines, alarm systems, paging systems, and various call types (e.g., long-distance, international, service numbers, and toll-free numbers). This can be done weeks before the cutover date which will provide you with ample time to test deployment.

  11. Cutover Execution:
    Execute the cutover plan based on the determined schedule, ensuring necessary physical connections and configurations are in place.

  12. Emergency Services Testing:
    Test 911 calls post-cutover to validate the correct address presentation to emergency dispatch units, prioritizing safety and compliance.

  13. Other Considerations:
    Redundancy and failover planning: Provider may have some redundancy options:
    If you have multiple integrations, the provider can schedule fallback to other locations.
    Fallback can be scheduled to mobile phones as well.
    QoS Configurations, if you have Data and Voice coming over the same path, provider can prioritize voice for incoming traffic.
    Important to document all changes.


At LookingPoint, we have leveraged our extensive expertise to facilitate numerous successful PSTN service transitions for our valued clients. Whether operating on-premises or within cloud environments, our dedicated efforts have empowered organizations to optimize their PSTN resources, achieve substantial cost reductions, and fully harness the array of benefits and advanced features offered by their chosen service providers.

As always if you have any questions and would like to schedule a free consultation with us, please reach out to us at sales@lookingpoint.com and we’ll be happy to help!

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Written By:

Freddy Tabet, Network Engineer

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