Usually, installation-wide interfaces to external services are defined in da.globals. However, this may not be practical on multi-tenanted installations where custom interfaces may be required for individual business IDs. To define a custom interface log in to the individual business ERP site and go to
Use Code Type: Interfaces and Code to name the interface and enter the interface parameters in the Property List box. The format should be exactly the same as you'd have used to define the same in da.globals. Two interface names, namely, SMS and Mail are reserved for defining SMS and email custom interfaces, respectively.
For an example, go to http://homepro.dreamapps.com and log in to the ERP site.