Implementing common PBX functions with Asterisk

Some PBX functions in Asterisk are implemented as applications or are supported by a combination of applications that you use in the dial plan. Next to that the different channels implement different subsets of CLASS (or Vertical Service) codes.

general support (for all channels)

• Music on Hold: Implemented in Asterisk. See MusicOnHold and musiconhold.conf.
• Call Parking: Supported in the standard installation
• Call Pickup: Supported in the standard installation (*8 - defined in res_features.c +55, modify pickupexten in features.conf)
• Call Recording: Using the 'Monitor' application
• Conferencing: Using the 'MeetMe' application
• IVR: Supported in extensions.conf through the Asterisk applications; employ AGI or EAGI if even more control is needed
• DISA: Direct Inwards System Access, Allows someone from outside the telephone switch (PBX) to obtain an "internal" system dialtone.
• Voicemail: Voicemail System, For unavailable or busy or no answer status, call can be automatic routed to Voicemail system. Voicemail system has many more attractive features.

for SIP Phones

• Call Hold: Normally implemented by your phone
• Unattended Transfer (or "blind transfer"): Implemented in Asterisk (#), optionally also in the phone
• Consultation Hold: Normally implemented by your phone, for
• Unconditional Call Forwarding
• Attended Transfer (or "consultative transfer")
• No Answer Call Forwarding: Implemented by yourself in the dial plan. See the tips & tricks page for ideas
• Busy Call Forwarding:Implemented by yourself in the dial plan. See the tips & tricks page for ideas
• Single-Line Extension:
• 3-way Calling: Normally implemented by the phone
• Incoming Call Screening: Implemented by yourself in the dial plan
• Find-Me:
• Call Pickup: Supported in the standard installation
• Outgoing Call Screening: Implemented by yourself in the dial plan
• Automatic Redial: You should be able to implement this in the dial plan with some AGI support
• Manual Redial
• Do-not-disturb (DND)
• Message waiting (MWI): Implemented in Asterisk, but must be support on the phone
• Call waiting indication: Implemented in Asterisk, but must be support on the phone

---

for Analogue Phones connect to Zaptel channel

See Asterisk vertical service activation codes for ZAP channels

• Call Hold: Normally implemented by your phone
• Unattended Transfer (or "blind transfer")
• Consultation Hold: Normally implemented by your phone, for
• Unconditional Call Forwarding
• Attended Transfer (or "consultative transfer"): See Asterisk tips zap transfer
• No Answer Call Forwarding: Implemented by yourself in the dial plan. See the tips & tricks page for ideas
• Busy Call Forwarding:Implemented by yourself in the dial plan. See the tips & tricks page for ideas
• Single-Line Extension:
• 3-way Calling: Normally implemented by the phone
• Incoming Call Screening: Implemented by yourself in the dial plan
• Find-Me:
• Call Pickup: Supported in the standard installation
• Outgoing Call Screening: Implemented by yourself in the dial plan
• Automatic Redial: You should be able to implement this in the dial plan with some AGI support
• Manual Redial

• Do-not-disturb (DND)
• Message waiting (MWI): Implemented in Asterisk, but must be support on the phone

.....Improved by Nahid Hossain

for MGCP Phones

See Asterisk MGCP channels

• Manual Redial: Normally implemented by your phone
• Unattended transfer (or "blind transfer"): Implemented in Asterisk (#)
• Attended transfer: Implemented in Asterisk (FLASH)
• Call Forwarding: Implemented in Asterisk (*72 and *73); optionally implemented in the phone
• Call Pickup: Implemented in Asterisk (*8)
• Call Waiting Indication: Implemented in Asterisk; disable with *70
• Call Number Delivery Blocking: Implemented in Asterisk (*67)
• Do-not-disturb (DND): Normally implemented by your phone; also implemented in Asterisk (*78 and *79)
• Message waiting (MWI): Implemented in Asterisk, but must be support on the phone

on the CAPI channel

See Asterisk CAPI channels

• Call Deflection (CD) (redirect without answering): Implemented by chan_capi
• CLIP & CLIR (display caller ID & hide my caller ID): Implemented by chan_capi
• CID & DNID: Implemented by chan_capi
• HOLD & RETRIEVE: Hold a call using ISDN (not the PBX): Implemented by chan_capi
• Early B3 Connects (always,success,never): Implemented by chan_capi
• DID (for Point to Point mode): Implemented by chan_capi

• ECT (explicit call transfer): Preserve the orginial CID - Implemented by chan_capi

See also

• PBX Features
• CLASS standard of vertical service codes
• Asterisk vertical service activation codes for ZAP channels
• John Todd's list of PBX features as Excel sheet
• dialparties

---

• Asterisk: Start page | Introduction | FAQ | Tips & Tricks