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Sending and Receiving Faxes

Aculab Cloud supports sending and receiving faxes from UAS or REST applications. To enable fax sending and/or receiving you must enable it on the relevant inbound or outbound service. If basic fax operation is all that is required, you can skip the following sections. Some fax users may want more control over the fax communication, and for these users we provide a number of advanced Fax settings.

Aculab Cloud supports the tiff image file format for sending and receiving faxes. See Supported Fax Formats for more detail.

 We support inbound fax for numbers in the US, Canada and the UK. We may well support it for numbers in other countries as well, but we'd like to try it first. So, if you'd like fax numbers in another country, please tell us.


Fax settings are set in the inbound and outbound service fax tabs. REST applications use these settings unmodified. For UAS applications, these settings serve as defaults and can be overridden via the UAS fax API. The service settings are used during the fax negotiation phase, during which the two fax endpoints will determine which settings are suitable; this depends on the endpoints' capabilities and on line conditions.

The basic settings are Mode and Subscriber ID. Advanced settings require a more thorough understanding of the fax protocol as improper use of these settings can lead to increased failure rates and interoperablilty problems. If you have questions our expert support team is always available to answer questions you may have regarding fax settings.

The UAS fax API allows you to examine the negotiated settings in use as key:value pairs. The REST API allows you to examine a subset of these. See Settings reported by fax negotiation.

Success Rates

Achieving a high success rate when sending and receiving faxes on the Cloud can be a challenge, not due to the Cloud itself, but due to the nature of global telecoms networks. It's more reliable in some countries than others and, even within one country, more reliable in some areas than others. As such, we strongly recommend that you thoroughly test your service before deploying it. We would also recommend that you use our PSTN providers for fax. That way, if there are problems we're in the best position to sort them out. If you are having problems sending or receiving faxes reliably, please tell us well before you want to deploy your service and we'll work to fix them.