Steve Harrington from tIPicall commented "T38 is the protocol for fax on SIP but many of the major carriers in the UK and globally do not support T38 and if they do they certainly do not guarantee it. G711 is also possible and often easier to use but still has no guarantees.
One of the main problems is international delivery. End carriers abroad may not take the transmission and complete the call so rendering any critical fax requirement by an end user as unworkable."
Another factor is the PBX environment on site. Harrington continued "Some systems handle fax better than others and some are very restrictive on which protocols they use and how it should be set up."
So what are the alternatives? "If a customer has to have fax for inbound and outbound and it is critical to their business, for example law firms, then they should either stick to their current fax methods and if that is not possible move to digital fax services for example eFax."
In order to fill this gap tIPicall have teamed up with eFax to allow customers to at least maintain their current requirements and in many cases drastically improve them. Providing inbound and outbound fax services digitally has been available for a long time however Harrington believes that there is now a new demand for eFax services which integrate with the new SIP environment.
“Electronic fax and SIP work very well together as we can keep the end users current numbers and provide and enhanced service. Whilst the decline of fax is well documented, it is still mission critical for a number of organisations and as such we need to be able to offer the full range of landline services for every customer.” comments Harrington.