PBX and SIP Provider:
A Beautiful Friendship

As you may already know if you’re reading this page, a SIP provider offers a SIP trunking solution, which connects to a Private Branch Exchange (PBX) on the one hand, and to the internet and the Public Switched Telephone Network (PSTN) on the other hand. A SIP trunk is a bundle of virtual telephone lines whose calls are managed using the Session Initiation Protocol (SIP), and whose voice data is sent as digital packets over the internet, for some or all of the call’s route.

A PBX is a business solution for managing internal phone communications, and for managing external communications on fewer physical (or virtual) phone lines than the number of extensions. This is possible because not all extensions are making external calls simultaneously. Nowadays, a PBX solution may be a combination of hardware and software, or it may be a pure software (virtual) solution.

The two types of products—PBX and SIP provider—must work hand-in-glove to provide a seamless Unified Communications solution. You may be considering acquiring the two products, or you may already have a PBX and are shopping around for a SIP trunking provider. In both cases, it’s helpful to understand how the two systems work together.

The SIP provider allocates trunk lines that connect to the customer's PBX, and assigns a range of Direct Inward Dialing (DID) numbers to the customer. Incoming calls to the DID numbers are forwarded to the customer's PBX through the trunks. The PBX routes the call to the correct extension, which is usually indicated by the last 3 or 4 digits of the dialed number. For outgoing calls, depending on the target number, the SIP solution routes the call either entirely over the internet, terminating at another SIP provider, or to a PSTN.

Given their complementary roles in managing business Voice-over-IP (VoIP) communications, it makes sense that PBX providers and SIP trunking providers cooperate, test out their integration and make it as painless as possible for their mutual customers. DID Logic has done just that with 3CX, a provider of a virtual (software-only) PBX solution for Windows and Linux, for on-premise or in-the-cloud installation.

3CX has designed a suite of certification tests that SIP solutions must undergo in order to verify integrability with their PBX software. DID Logic is a 3CX-certified solution, which means that the functionality and quality of the combined 3CX/DID Logic solution has been proven and is recommended to customers. Best of all, when deploying a 3CX solution, integrating with DID Logic is simply a matter of choosing DID Logic from a pre-defined menu of supported providers. The 3CX configuration wizard then automatically fills in other fields required for the integration, such as authentication credentials.

If you’re an existing or potential customer of 3CX, completing your VoIP infrastructure with DID Logic’s solution increases your cost savings and guarantees a solution with proven reliability and turnkey integration.