How Are You Encouraging Direct Inward Dialing, or DIDs, Both Inbound and Outbound?

How Direct Inward Dialing Operates?

DIDs (Direct Inward Dialing) route incoming and outgoing calls on IP PBX systems. Most IP PBXs have mechanisms for DIDs, but questions often arise about related products and setup.

Many businesses acquire DIDs (Direct Inward Dialing) using traditional analog phone lines (POTS), provided by their local carrier. These are similar to residential landlines and popular in small offices due to their lower cost. Typically, 4-8 lines are used based on call volume.

Each analog POTS line provides one dedicated channel and is linked to one DID (Direct Inward Dialing) number. So, four POTS lines equal four available channels for calls.

Taking Voip out of the frame for a moment.

In a traditional setup, analog phones directly connect to separate PSTN lines, each with a unique DID number. With VoIP, those lines connect to an IP PBX instead. FXO cards in the PBX enable this connection. For example, if you have eight analog lines, you'd need a card like the Sangoma A20004D or Digium AEX808E to interface with your PBX.

By connecting your analog lines to FXO cards in your IP PBX, you can configure DIDs within the system. Most IP PBXs will automatically detect these cards. VoIP phones aren't tied to specific DIDs anymore; they use the next available one within the group, allowing for more VoIP phones without adding more physical POTS lines.

Essentially, you need fewer POTS lines than VoIP users. For instance, 8 POTS lines can handle 16 VoIP users if only 8 call simultaneously. FXO cards aren't limited to 4 or 8 ports, this was just an example. Check out voipsupply.com for more on Sangoma and Digium cards.

Digital connections, like T1 lines, are becoming popular alternatives to analog POTS lines for larger businesses due to their cost-effectiveness and ability to handle higher call volumes. A T1 line provides 24 voice channels (like 24 analog lines bundled together). Most IP PBXs can accommodate T1 lines using external gateways or digital PCI cards.

Two T1 Provisioning Types

T1s are provisioned in two ways: PRI and CAS. PRI offers 23 usable channels, with the remaining one for signaling. CAS allows all 24 channels for voice, data, or both. Each channel handles its own signaling. Confirm with your provider which type they use, then choose the best fit for your needs.

Connecting T1 lines to IP PBXs is easy. Simply plug your T1 into a single T1 card (like the Digium TE-122P or Sangoma A101). Most T1 cards support multiple T1 lines, offering up to 96 channels. For larger applications, check out the Digium TE-420B or Sangoma A104D card.

SIP Trunking

SIP Trunking is another DID option, delivered over your internet connection (like T1, fiber, or cable). It's gaining popularity due to its cost-effectiveness and no need for physical lines. However, availability varies by region, so check with your VoIP provider before choosing this option.

SIP Trunking, a cloud-based solution, is growing in popularity. It's cost-effective and eliminates the need for physical lines. While availability is still limited, more providers are expected to offer it soon. As demand increases, it will likely become a standard option for businesses of all sizes.