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This guide will walk you through the simple process of activating your trial for Elastic SIP Trunking (EST), understanding its features and limitations, and how to request an upgrade to a full production account.   Activating your trial   Log in to your Sinch account. From the main dashboard, you'll see an overview of the products available to you. Note, if you’ve just signed up for an account, you will have some test credits you can use for Elastic SIP and other services.   Navigate to Elastic SIP Trunking. On the left-hand navigation menu, expand the Voice section and click on Elastic SIP Trunking. Start your journey. On the overview page, click the Activate trial button to begin.   Review the trial limitations. A modal window will appear outlining the limitations of the trial account. You’ll need to acknowledge these terms before proceeding. Your trial access to Elastic SIP Trunking comes with the following feature limitations: May only place calls to verified numbers. Calls are limited to 5 minutes in length. May only place calls with the following countries: Canada, Puerto Rico, United States, United States Virgin Islands. After you accept, a welcome message is displayed.   Navigating your trial account   Once your trial is active, you'll notice a banner at the top of the Elastic SIP Trunking pages indicating that you are using a trial version (and an option to request an upgrade).       Verified numbers are key   During the trial, you can only make calls to numbers that you have verified for your account. This is an important security measure. You can manage your verified numbers by navigating to Numbers > Verified numbers. For more information on how to add a verified number, please see our guide: How can I add a verified number to my account?     Build trunks   With your verified number you can create new SIP trunk(s) and start making calls. See more information on setting up Elastic SIP in the Getting Started with Elastic SIP community article. The cost of each call will be deducted from your test credits.   Upgrading to a full account   When you're ready to move beyond the trial limitations and unlock the full power of Elastic SIP Trunking, you can easily request an upgrade. From any Elastic SIP page, click on "Request Upgrade". You can find this button in the banner at the top of the page. Tell us about your needs. A pop-up will appear asking for a bit more information about your planned business use of EST. This will help our team understand your needs to ensure a smooth transition.   Submit your request. After you provide the necessary details, a member of our sales team will reach out to you to finalize the upgrade process. We hope this guide helps you get started with your Elastic SIP Trunking trial. If you have any questions, feel free to explore the rest of our community articles or reach out to support. ... View more

Call Blocking enables you to configure project-specific rules that filter calls based on your specified criteria. This can be as granular as blocking a specific number from being able to call your numbers, to blocking all calls on a project. Here‘s how to configure it.         Rule name   You can configure multiple rules within your project. To keep them organized, assign each rule a unique identifying name.   Direction   The rule's direction determines whether it applies to calls originating from or terminating at your SIP infrastructure. This direction is always defined from your SIP infrastructure's perspective. For example, 'Inbound' refers to calls from the Elastic SIP Trunking Service or PSTN directed towards your infrastructure. Conversely, 'Outbound' refers to calls your infrastructure sends to the Elastic SIP Trunking Service.   Matching criteria   The final step in creating a rule is to specify the matching criteria.   All Numbers – This criterion should be used if you wish to completely shut down all calls in a specific direction. For example, an inbound call center may want to disallow outbound calling completely. Numbers beginning with – This option will allow you to create a criterion which will block numbers beginning with the match pattern. For example, you could disallow calling to a specific NPA (Numbering Plan Area). Additionally, you can specify a full phone number here to block a specific individual from calling your numbers. Country – This criterion will allow you to specify a country. If applied to outbound calls, this will completely disallow calls to be made to that country. This rule will take precedence over your Country Permissions entry for that country.   ... View more

Currently, Elastic SIP Trunking is only available for North American business entities and can only be used with North American phone numbers. ... View more

Robocalls and spoofed caller IDs have become a massive issue. To fight back, the FCC introduced the STIR/SHAKEN framework — a system that lets carriers verify that a call really comes from who it says it does. What do you need to do to ensure your traffic is being signed correctly? If you are an enterprise customer, meaning a customer who is using their service just for their own business communications, you may choose to do nothing, as Sinch will sign calls on your behalf.   However, if you are a service provider, meaning you provide telecom services to other companies, then you are required by the FCC and the TRACED act to sign your own calls.   Enterprise Customer Responsibilities   Enterprises can choose to sign their own calls. When doing so, Sinch will ensure the signing and attestation remains intact as it transits our network. When Enterprises send unsigned calls from Sinch provided numbers (or numbers you have ported to Sinch), Sinch will sign them with an “A” attestation, the highest level of trust possible. Enterprises sending unsigned calls from non-Sinch numbers, will be signed with a “B”. This indicates that while we know who the Enterprise is, we have no knowledge about the calling party number.   Service Providers - You’re Required to Sign Your Own Calls   The FCC requires all voice service providers — including gateway providers and intermediate providers — to sign all outbound IP-based calls using your own STIR/SHAKEN certificate. You should have your own SPC token (from the STI-PA), certificate, and ability to sign calls. Like the enterprises above, any calls that have been signed prior to reaching Sinch will remain as they transit through the Sinch network.   By the same FCC rules, Sinch, as an intermediate provider, is legally required to sign any unsigned calls we receive. Unsigned calls from service providers on EST will be signed with a “C” attestation , meaning we don’t know or can’t vouch for the caller ID, which may increase the likelihood of calls being labeled as “Likley SPAM”.   Have Questions?   We recommend discussing your STIR/SHAKEN strategy with a telecom regulatory advisor or one of the approved certification authorities — but if you have questions about how Sinch handles unsigned calls or would like to talk about Sinch Hosting your certificate on our infrastructure, we’re happy to help. ... View more

Elastic SIP Trunks can be configured with Forwarding / Fallback. Once set, if a call to one of the telephone numbers associated with a trunk cannot be completed over any of your SIP Endpoints (or in the event you have disabled/removed them) the call will immediately forward out to the number you have configured. To forward all calls simply create a trunk without any SIP endpoints, associate phone number(s) and turn on Forwarding. This option can be configured under the Inbound Call Settings on your trunk.     Additionally, once this is enabled the route will display on your SIP Endpoints section.  This provides a visible reminder that it is enabled and will be used as the route of last resort for your telephone numbers.   ... View more

SUBSCRIPTIONS: If you want to subscribe to updates for Elastic SIP Trunking, click the Options menu button in the right-hand-corner of this article and select Subscribe. You will then receive email notifications when this article is updated with new release notes.   Check in here to see information about new releases from Elastic SIP Trunking.   8/4/2025 - Call Blocking   Sinch Elastic SIP Trunking customers may now create rules which will allow them to block incoming or outgoing calls based on pre-configured match criteria. More information on this feature can be found here.   6/24/2025 - Elastic SIP project activation via API   Once your account has been enabled for Elastic SIP Trunking, you are now able to activate any of the projects on your account via the API. API Endpoint documentation for this feature can be found here.   6/24/2025 - G.711 A-law   Elastic SIP Trunking trunks now support G.711 A-law. This codec is already enabled and will be offered in the SDP for Inbound calls. Outbound calls which request it as a priority codec will have it negotiated.   5/2/2025 - Call Forwarding/Fallback   Elastic SIP Trunking trunks may now configure a phone number which all calls will be forwarded to in the event we cannot reach the customer’s infrastructure.     4/16/2025 - Call Detail Record and Reporting Enhancement   Elastic SIP Trunking call records and analytics now include the ability to select multiple projects at the same time.     3/17/2025 - Call Detail Record (CDR) Enhancements    Elastic SIP Trunking call records will now include the calculated MOS (Mean Opinion Score) as well as the transport protocol which was used.     2/27/2025 - Elastic SIP Trunking Expansion to US-West Datacenter   Elastic SIP Trunks can now be configured to use our East coast or our West coast datacenters. There are now additional regional domain names found on your SIP Trunk configuration page which can be used to send your traffic to the datacenter of your choice. Customers using registered trunks should send directly to US-East only using the <customer domain>.us-east.pstn.sinch.com as inbound calls will experience call completion issues over US-West. This will be resolved in an upcoming Maintenance.     2/27/2025 - Packet Captures (PCAPs) are now available for customer calls   Customers can now download a packet capture of their calls from the Sinch Dashboard. Selecting any Call Detail Record in the dashboard will now show an option to download the PCAP. Currently PCAPs are not available for Registered calls, or calls using Encryption. Both will be added soon.     1/17/2025 - Inbound Digest Authentication   Elastic SIP Trunks can now be configured to respond to authentication challenges by the customer infrastructure. ... View more

A Point of Presence (or POP) is the physical location of a network provider's, internet service provider's (ISP), or telecom carrier's network equipment which enables connectivity for their services. It is an access point for users, businesses, and other networks to connect to and use the provider's services and infrastructure. ... View more

All Sinch Elastic SIP Trunks support TLS and SRTP natively. For more information on TLS/SRTP encryption and the benefits of using it, please read more here.   To make encrypted calls with TLS simply send calls to your SIP Trunk FQDN on port 5061.   This port can only be used for TLS, and non-TLS calls will fail.  SRTP must be used when making a TLS call.   To ensure we send calls to your infrastructure using TLS go into your SIP Endpoint on your SIP Trunk and change the transport protocol to “TLS”.  Note, that the port on your SIP endpoint will update automatically to port 5061.  In the event your infrastructure is listening for TLS connections on a non-standard port simply change the port manually to the correct value.     Congratulations, your Sinch Elastic SIP Trunk is now configured to use encryption!  It’s that easy.   Let's Encrypt Certificates   Sinch Elastic SIP Trunking uses TLS certificates secured by Let’s Encrypt.  If your TLS SIP Infrastructure does not already trust certificates from this Certificate Authority you can download the Let’s Encrypt Root Certificate and associate Intermediate certificates here: https://letsencrypt.org/certificates/   Cypher Suite Support   Sinch trusts all well-known Certificate Authorities.  This ensures we will not have any trust issues when your infrastructure presents its certificate on inbound calls.   For negotiation Sinch supports the following Cypher Suites for both TLS and SRTP.   TLSv1.2   TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8 TLS_ECDHE_ECDSA_WITH_AES_256_CCM TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 TLS_ECDHE_ECDSA_WITH_AES_128_CCM TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA   TLSv1.3   TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 TLS_AES_128_GCM_SHA256 ... View more