Communication Error: What Causes It

What Is a Communication Error?

A communication error is a fax transmission failure that happens after a call has already connected, caused either by the call disconnecting before the fax finishes transmitting (often because the recipient hangs up early) or by noise and interference on the phone line disrupting the signal mid-transmission. It's distinct from other common failure types: a busy line, an unanswered call, and a failed handshake negotiation are each logged and handled as their own separate error, not as a communication error.

Where a Failure Actually Happens

A communication error can surface at more than one point once a call has connected. It can appear right at the start, during the initial handshake negotiation, in the middle of the actual page-data transfer, or as the connection drops entirely before either stage finishes. Distinguishing which stage failed matters more than the generic label itself, since a negotiation-stage failure and a transfer-stage failure usually point to different underlying causes.

Many fax devices also display or print a specific numeric or alphanumeric error code alongside a communication error. That code is defined by the device's own manufacturer, not by a shared fax standard, so the same number can mean something different from one machine to the next. Reading what a particular code actually means requires checking that specific device's own documentation rather than assuming a universal meaning.

Communication Error and Auto Retry

Because a communication error often comes from a transient issue, a moment of line noise, a call that dropped for an unrelated reason, Fax.Plus can automatically redial and resend the fax, up to 3 attempts with a delay the sender configures. The same mechanism also responds to a busy line or an unanswered call, so a communication error is only one of several triggers, not the only one.

Partial Sends and Auto Resume

A connection error does not always mean restarting from the first page. When Auto Resume on Partial Send is enabled, Fax.Plus can continue a partially delivered fax from the next unsent page. The continuation is a separate fax transmission and can still fail if a blocking error persists. Auto Retry on Failure is a separate setting.

A Note on Credit and Failed Attempts

If the call connected and ran for any length of time before a communication error ended it, credit is still deducted for that attempt, since telecom providers bill by call duration regardless of whether the fax completed. This applies the same way whether the fax was a single-recipient send or one leg of a fax broadcast going out to several recipients at once, where one leg failing with a communication error doesn't affect the others.