Unlike unconditional forwarding (which sends every call away immediately), conditional call forwarding lets your phone ring first and only diverts the call when you are busy on another line, unable to answer within a set number of seconds, or out of cellular coverage.
The Three Types of GSM Conditional Call Forwarding
Defined by the 3GPP TS 22.082 standard, mobile networks worldwide support three distinct conditional forwarding triggers that can be configured independently via USSD/MMI star codes:
- Call Forwarding on Busy (CFB —
*67*number#): Triggers immediately when you are already on an active call or tap “Decline”. - Call Forwarding on No Reply (CFNRy —
*61*number*seconds#): Triggers when your phone rings for 15–30 seconds without being picked up. - Call Forwarding on Not Reachable (CFNRc —
*62*number#): Triggers when your phone is powered off, in airplane mode, or in an elevator/dead zone.
Why Conditional Forwarding Cuts AI Receptionist Costs by 60%
When you pair conditional call forwarding with Kolivri’s per-minute AI voice agent plans, you answer the calls you are free to take and only consume AI minutes on the overflow calls you would have otherwise missed.
Standard 3GPP GSM Conditional Forwarding Star Codes
| Condition | Activate Code | Deactivate Code | Erase / Reset Code |
|---|---|---|---|
| When Busy (CFB) | *67*Destination# |
#67# |
##67# |
| When No Answer (CFNRy) | *61*Destination# |
#61# |
##61# |
| When Unreachable (CFNRc) | *62*Destination# |
#62# |
##62# |
| All Conditional Forwarding Together | *004*Destination# |
#004# |
##004# |
Key Resources, Internal Guides & Official Standards
To explore related implementation playbooks and official industry standards, review these internal and external resources:
- After-Hours & Overflow AI Answering — 24/7 backup for busy and unanswered calls
- AI Voice Agents for Trades & Field Services — Capture jobs while on site
- Kolivri AI Voice Agent Pricing — Flexible minute bundles starting at $69/mo
- 3GPP TS 22.082 Call Offering Supplementary Services ↗ — Official GSM standard for CFB, CFNRy, and CFNRc
- Google Phone App Call Forwarding Help ↗ — Managing conditional forwarding on Android devices
Frequently Asked Questions (FAQ)
How do I change the number of seconds before conditional forwarding triggers?
Append *seconds# (in 5-second increments from 5 to 30) to the *61* code: for example, *61*Number*15# forwards after 15 seconds.
How do I cancel all conditional call forwarding at once?
Dial ##004# to erase only conditional rules, or ##002# to erase all unconditional and conditional forwarding rules.
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