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DAHDI Channels

A DAHDI channel is based on TDM transmission with support for EuroISDN, Q.SIG signaling and E1/T1 bandwidth.

The channel functions as an inbound/outbound communication path with service provider PBXes or other branch PBXes. DAHDI channels must be assigned to inbound routing to process incoming calls. Without assignment they remain inactive. Outgoing calls use either the “Dial channel” application in inbound routing, or channel assignment in outbound routing rules.

DAHDI channels

Creating, editing and deleting a DAHDI channel

New DAHDI channels are created after installing an E1/T1 card (Digium or Sangoma) and manually running the dahdiSetup.php script. Settings are edited using the Edit button or via the right-click context menu on the selected DAHDI channel.

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DAHDI channel properties

DAHDI channel properties

  • Port number (SPAN) — TDM port number
  • Active — port activation/deactivation
  • Bandwidth type — E1 (30 channels) or T1 (24 channels)
  • Signaling protocol — EuroISDN, Q.SIG or National (ISDN2)
  • Name — port designation
  • Caller number — identification number for outgoing calls
  • First channel — first channel number
  • Number of channels — number of active channels
  • Overlap dialing — enable progressive number completion
  • Tone indication — Out-of-band or In-band
  • Signaling — CPE (customer side) or NET (operator side)
  • Synchronization — Master (provides sync) or Slave (expects sync)
  • CRC4 — cyclic redundancy check activation
  • Tariff — billing table selection
  • Prompt language — default prompt language
  • Echo cancellation — No, Yes, 32ms (4ms), 64ms (8ms), 128ms (16ms) or 256ms (32ms)
  • Echo test — ECHO training — automatic echo test after pickup
  • Call limit — maximum number of concurrent calls
  • Channel allocation — Lowest free channel, Highest free channel, Lowest cyclic, Highest cyclic
  • Bundle — channel binding with other ports
  • Relax DTMF — improved DTMF detection preventing duplicates
  • DTMF tone duration — transmitted tone duration in milliseconds
  • PRI numbering plan type — Unknown, Private, Local, National, International, Dynamic or Redundant (incoming)
  • PRI local numbering plan type — numbering scheme for outgoing calls
  • PRI connected numbering plan type — numbering scheme after connection
  • International prefix — prefix for international calls
  • National prefix — prefix for national calls
  • Local prefix — prefix for local calls
  • Private prefix — prefix for private calls
  • Unknown prefix — prefix for unknown numbering plan
  • B-channel reset interval — periodic reset of unused channels (in seconds)
  • Force restart of unavailable channels — forced restart of unavailable channels
  • Inband on setup ACK — in-band acknowledgment messages
  • Inband on proceeding — in-band audio during proceeding (e.g. unavailability announcements)
  • Inband disconnect — in-band audio after disconnect (e.g. busy tone)
  • Send ISDN data in IE — Block, Initial name, Update name, Name or Text
  • Receive ISDN data in IE — Block, Initial name, Update name, Name or Text
  • Allow sending malicious CID (MCID) — malicious caller identification transmission
  • Send date and time — Date only, Date and time, Date/time/minute or Full timestamp
  • Connected party identification display (COLP) — Block, Connect or Update
  • ISDN supplementary services support — extended ISDN services support
  • Billing support — S (before call), D (during call), E (after call) or combination
  • Delay call termination per AOC-E — postpone call termination until AOC-E arrival or T305 expiry
  • Hardware type — TDM card type
  • Hardware name — TDM card name
  • PCI slot — occupied PCI slot
  • PCI bus — occupied PCI bus
  • Echo cancellation method — hardware vs. software echo cancellation
  • Note — informational text

General settings

General settings

General settings apply to all DAHDI channels but can be overridden by individual channel settings. Kernel driver module parameters and tone scheme configuration are also available.

  • Bandwidth type — E1 (European, typically 30 channels) or T1 (24 channels)
  • Kernel module settings — custom driver module parameters
  • Tone scheme — country-specific tone scheme selection

DAHDI bundles

DAHDI bundles

DAHDI bundle configuration and free channel allocation methods.

  • Channel allocation — channel assignment strategy:
    • Lowest free channel (always the lowest available)
    • Highest free channel (always the highest available)
    • Lowest free channel cyclic (lowest, then ascending)
    • Highest free channel cyclic (highest, then descending)
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