Zentrunk Hero


Zentrunk is Plivo’s SIP Trunking service that provides global coverage for your outbound and inbound voice calls. More than just a regular SIP Trunk, Zentrunk works with your current cloud or on-premise communications infrastructure. Whether you’re looking to increase the capacity of your current telecom stack, increase coverage and phone number inventory, or extend your on-premise infrastructure to the cloud, Zentrunk can get you started instantly. No minimum spends, carrier negotiations, or long-term contracts required, you can provision SIP Trunks instantly through our user interface.

Why Zentrunk?

Plivo’s Zentrunk provides various benefits to your business, such as:

Scalability: Zentrunk supports your organization’s need for fast growth across multiple geographic locations. By combining your voice and data into a single network, SIP trunking also allows your organization to scale with extreme flexibility as you open new sites or establish full-time remote workers. You can scale as you grow by adding more local and international numbers. Plivo provides Local, Mobile, and Toll-Free numbers in over 70 countries, all of which you can purchase from your Plivo Console, and upon purchasing, you can configure them in your trunk, and start terminating calls from your IP-PBX. We recommend using local Plivo numbers for each region to have a strong local presence. You can also make calls to over 190 countries using Zentrunk to make your business more globally accessible.

Cost Savings: With traditional phone service, your organization is subject to different, often variable charges for your local, long distance, and international calling. Moving from these traditional telecom systems to SIP trunking will help you save a lot of recurring costs, as you can build the entire telecom system on the cloud, and be billed on a simple per-usage basis. You can also avoid any physical infrastructure and hardware investments that typically come with scaling phone lines. With Zentrunk, adding phone lines or add-on services is as simple as purchasing an additional handset and scaling your monthly service agreement.

Reliability: Traditional phone systems are prone to interruptions such as weather events, networking issues, etc. whereas SIP trunking is reliable as you can add failover if the primary IP is not responsive. With a redundant infrastructure across multiple geographies and at least three local carrier connections across countries, Zentrunk promises a 99.95% uptime.

Easy Management For Your IT Teams: Your IT team will never have to use their mobile device to wait on hold to speak to a customer service representative again. SIP trunking and VoIP phones offer easy-to-use administrative portals for on-site management, including actions like adjusting call routing, changing extensions, or adding phone lines fully on-demand

Our 24x7 premium support and consultative customer success team will provide you with all the technical guidance when you need it.


Plivo account

When you sign up with Plivo, you will start with a free trial account to experiment with and learn about our services. This free trial account comes with free credits. If you wish to continue with our service, you can add more credits and purchase a number by clicking here. Add a number and credits to your account to start testing the full range of our voice and SMS service features.

Sign up here to get your free Plivo account today. Follow these steps to successfully sign up for a free trial account:

  1. Sign up with your work email address
  2. Check your inbox for an activation email from Plivo. Click on the link in the email to activate your account.
  3. Enter your mobile number to complete the phone verification step.

Sign up with your work email address

Sign up with email addres

If you have any issues creating a Plivo account, please reach out to our Support Team for assistance.

Supported devices for SIP-trunking

  • All major IP-PBXes supported, (You can find the supported PBXes here).
  • SIP-based hardphones or softphones.
  • For any application or browser-based calling, Zentrunk supports integrations with webRTC clients or endpoints.

Supported SIP methods

Zentrunk currently supports the following SIP methods: ACK, BYE, CANCEL, INVITE, and UPDATE.


Supported Codecs

Plivo Zentrunk currently supports G711 U-law (PCMU) and A-law (PCMA).

Signaling IP addresses

You may need to whitelist Plivo IPs in your firewall to ensure that calls get routed without interruption. Please ensure that you whitelist all the IPs mentioned as the calls might get routed through a different region in an unlikely event of service disruption in a specific region.

The following is the list of IP addresses that you would need to whitelist.

Regions IP Addresses Signalling Ports Media Ports
North California, USA 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)
Virginia, USA 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)
Frankfurt, Germany 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)
Sao Paulo, Brazil 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)
Sydney, Australia 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)
Singapore 5060 (UDP/TCP)
5061 (TLS)
10000 - 30000 (UDP/TCP)

Internet Bandwidth

SIP Trunk calls over the Internet would require sufficient bandwidth to support peak concurrent call traffic. Plivo needs about 100kbps for every successful call.

Depending on the peak concurrent calls, the bandwidth requirements can be calculated as: Minimum bandwidth Requirement = 100kbps * Peak Concurrent calls

Outbound Trunks (Termination)


Outbound SIP Trunking

Zentrunk’s Outbound SIP Trunks enable you to reach fixed and mobile phones in 190+ countries. There are no restrictions or limitations on channels or ports. Each trunk comes with unlimited concurrent call capability. Get all the standard features of a Telco (i.e., dynamic CLI, DTMF support, per-second billing) and more (e.g., secure trunking, fraud detection, instant provisioning). You only pay for what you use, with no long-term contracts.

Create an Outbound Trunk

You need to set up the trunk authentication on the Plivo Console to use Zentrunk to terminate calls. Authentication of your trunk ensures that Zentrunk only accepts traffic that your infrastructure sends securely. You can configure your trunk to be authenticated by an IP Access Control List, a Credentials List, or both. For more information, please check the step-by-step GIF & instructions below.

Outbound SIP Trunking

To create an Outbound Trunk:

  1. On the Outbound Trunks page in your Plivo Console, click Create New Outbound Trunk.
  2. In the New Trunk window, enter a name for your trunk (for example, Plivo Test).
    Note: By default, the trunk is enabled.
  3. Under Trunk Authentication, select the IP Access Control List, the Credentials List, or both.
    Note: Make sure you choose either an IP Access Control List or a Credentials List. The "IP Access Control List" shall provide a list of the IP addresses from which the SIP Invite will be accepted for this trunk. The "Credentials List" will provide a username and password that will be used to authenticate the SIP Invite.
  4. To Create an IP Access Control List:
    1. To add a new IP Access Control List, click + Add New IP ACL.
    2. In the ‘Create New IP Access Control List’ window, enter the name for your IP Access Control List (for example, TestACL) and then enter the IP addresses to be whitelisted in the IP Address List field.
      Note: You can add multiple IP addresses that are separated by a comma.
    3. Click Create ACL to save and add your IP Access Control List.
  5. To Create a Credentials List:
    1. To add a new Credentials List, click + Add New Credentials List.
    2. In the ‘Create Credentials List’ window, enter the name for your Auth Group (for example, TestCredList), Username, and Password.
    3. Click Create Credentials List to save and add your Credentials List.
  6. Select the IP Group and Auth Group, click Create Trunk. Your Outbound trunk will be created.

Secure Trunking on Outbound Trunks

Information security plays a vital role in any business, and to ensure that the information shared between your communication infrastructure and Plivo Zentrunk is secure, we recommend leveraging the Secure Trunking feature. You can secure your trunk by encrypting and authenticating the data packets involved for a SIP call over the internet. The two types of data packets involved in a SIP call are:

  • Signaling
  • Media

Encrypt Signaling Packets

You can encrypt signaling by using TLS (Transport Layer Security) protocol. Communication over TLS ensures authentication between two transport endpoints over an unsecured path for the SIP messages. TLS versions supported are TLS 1.0, TLS 1.1, and TLS 1.2.

  • If Secure Trunking is enabled: Zentrunk will communicate with your PBX or SBC over TLS for Signaling.
  • If Secure Trunking is disabled: The calls will be over TCP/UDP for Signaling.

Encrypt Media Packets

For securing the RTP packets (media), Secure Real-Time Protocol (SRTP) is used.

  • If Secure Trunking is enabled: Zentrunk will communicate with your PBX or SBC over SRTP for Media.
  • If Secure Trunking is disabled: The calls will be over RTP for Media.
Note: You can use SRTP regardless of the SIP signaling messages being on TCP/UDP. However, Plivo strongly recommends you enable a secure mode of communication between your infrastructure and Zentrunk.

Enable Secure Trunking

To enable Secure Trunking for an outbound trunk refer to the following GIF and instructions:

Outbound SIP Trunking

  1. On the Outbound Trunks page in your Plivo Console, click Create New Outbound Trunk.
  2. In the New Trunk window, enter a name for your trunk (for example, Plivo Test).
    Note: By default, the trunk is enabled.
  3. Under Trunk Authentication, select the IP Access Control List, the Credentials List, or both.
  4. Select the IP Group and Auth Group, click Create Trunk. Your Outbound trunk will be created.
  5. Under Secure Trunking, use the “Disabled/Enabled” toggle button to enable secure trunking.
    Note: By default, secure trunking is disabled.

Inbound Trunks (Origination)


Inbound SIP Trunking

With Zentrunk, you can instantly access the inbound phone number DIDs in Plivo’s more than 5 million phone number inventory representing more than 60 countries. Each phone number comes with unlimited concurrent call capacity. Zentrunk customers can also instantly search, filter, and provision fixed, mobile, toll-free, and SMS-enabled phone numbers through the Zentrunk API or user interface. Also, our carrier team will help you to port your phone numbers to Zentrunk from your current provider.

Create an Inbound Trunk

Inbound SIP Trunking

To create an Inbound Trunk:

  1. On the Inbound Trunks page in your Plivo Console, click Create New Inbound Trunk.
  2. On the New Trunk window, enter a name for your trunk (for example, Plivo Inbound).
    Note: The Enabled checkbox is selected by default.
  3. Select the Primary URI and Fallback URI of your PBX.
    Note: The Primary URI is the FQDN or IP address to which all calls are forwarded first. If the Primary URI is unresponsive, the calls will be forwarded to the Fallback URI.
  4. To add a new Primary or Fallback URI, click Add new URI.
  5. On the Create URI window, enter a name for your URI (for example, inbounduri), and then enter the URI (the FQDN or IP Address of your VoIP infrastructure).
  6. To enable Authentication, click on the Authentication option and provide username & password.
  7. Click Create URI to save and add your URI.
  8. Once you have created and selected your Primary and Fallback URI, click Create Trunk. Your inbound trunk will be created.
  9. Assigning an inbound trunk to a Phone Number
    1. Once you click on Create Trunk in the next window, you can link your trunk with Phone numbers.
    2. You can either link the trunk with your existing phone numbers in your account or buy a new phone number and link the trunk.
    3. If you wish to use your existing numbers, select the phone numbers under the Current Phone Numbers section, and click Link Selected Numbers.
    4. If you wish to use a new number, navigate to the Buy New Number section and choose the country, prefix, type, capability, and click on Search.
    5. Select a Phone number and click Buy Number.
    6. Once you click on Buy Number, the number will be added to your account and the same will be linked with your inbound trunk.

To know more about buying a Plivo Phone number, please navigate to the Buy a number section.