What Are Fax Buffers?
- Nathaniel Halbrooks
- Kelli Higdon
Dahdi Buffer (Fax Buffers)
Many of the problems with fax pass-through are caused by inconsistent timing. Since faxes are more tolerant of latency than voice calls (a fax has to be able to travel halfway around the world, which takes a few dozen milliseconds), the introduction of a buffer in DAHDI (which is strictly used for faxes) has reportedly corrected many of the problems that have plagued fax pass-through.
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Immediate: Tell's DAHDI to not use buffers and as soon as any data is received it will be sent to the Asterisk core. Â
Half: (AKA Half buffer) DAHDI waits until half of its buffer get data before sending it to the Asterisk code. Â
Full: (AKA Full buffer) DADHI waits until all its buffer is filled with data before sending ti to the Asterisk core. Although some policies could cause a little latency, this shouldn't go above 30 ms.
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