Objective
Provide guidance for diagnosing and resolving fax failures on a Grandstream ATA HT801 that is registered and online but experiences inbound/outbound fax issues after relocation
Applies To
-
Grandstream HT801 ATA
-
Analog fax devices (e.g., Canon imageCLASS MF615iF)
-
8x8 PBX extensions configured for fax
-
Scenarios involving device relocation or environment change
Procedure
1. Extension & ATA Configuration Review
Verified extension xxxx configuration:
-
✅ Primary DID correctly assigned: xxxxxxxxxxx
-
✅ Codec: G.711u
-
✅ Fax Mode: T.38 enabled
-
✅ Call Waiting: Disabled
-
✅ Dial Plan: NANP-INTERNATIONAL (or whatever service needed)
-
✅ No restrictions applied
-
✅ ATA registered and online
Result: No configuration issues identified
2. Root Cause Identification
Further review identified:
-
Call forwarding rules were not configured
-
Extension was expected to forward on No Answer / Busy (rejected), but forwarding was unset
-
Extension profile contained over 100 voicemail entries, exceeding recommended limits and needed deletion
These conditions caused unpredictable call handling, directly impacting fax call completion.
Additional Information
-
Fax issues can be caused by PBX-level call handling, even when ATA and codecs are correct
-
Excessive voicemail entries can affect call processing
-
Always review:
-
Call forwarding rules
-
VM count on fax extensions
-
Extension behavior after relocation
-