Receiving a Busy Signal/Call Drop when an Auto Attendant Forwards out to an External Line 

Updated: 04/07/2026

Symptom

When using an Auto Attendant to dial out to an external line, you receive a busy signal/call drop. 

Applies to

  • Admin Console 
  • Auto Attendants

Resolution

For an Auto Attendant to forward calls out to an external number, the phone number receiving the inbound call must be assigned to a user or service first. An unassigned number will not support forwarding to an off‑net (external) destination.  You need to involve a user/number in some way:
 
  • One method would be to assign a number to the Auto Attendant. 
  • The second method is to assign the Auto Attendant’s 8x8 number to a user account, then configure that user’s call forwarding to the external number. Calls to the AA number are then forwarded out via that user’s forwarding rules.
  • Another method is to forward calls from the Auto Attendant to a user or ring group, and then configure that user/ring groups call forwarding rules to dial out to the external number.
 
The above approaches rely on a number being associated with either the Auto Attendant,  with a user or extension that handles the external forwarding. 
 
Note: Essentially, when placing a call to the Auto Attendant to forward out to the external line from the Auto Attendant that is not assigned to a number, there is no phone number to associate with the call, and the carrier rejects it with a 403 FORBIDDEN.
 

Causes

  • Concurrent external calls has been reached
  • No user/service/number is assigned to the Auto Attendant