How to seperate inbound and outbound for same SIP provider?

Dear all,

since two weeks, I am desperately trying to make Asterisk pass through faxes between a T.38 local SIP device and my provider (who supports T.38). Since I have all sorts of problems and nothing works, I have come to the conclusion that I probably have misunderstood some basic concepts regarding the dialplans and sip.conf.

I am working with pure asterisk (no GUI, no distribution). I have compiled Asterisk 13.0.1 and, while working through the example config files, have stumbled across the following section in the sip.conf example:

; Tip 1: Avoid assigning hostname to a sip.conf section like [provider.com]
; Tip 2: Use separate inbound and outbound sections for SIP providers
; (instead of type=friend) if you have calls in both directions

So, these are my first two questions:

  1. How do I separate the inbound and outbound sections? During my research, I have not seen an appropriate example, so could anybody give one?

  2. There doesn’t seem to be any documentation about which of the configuration directives in sip.conf are only valid for a certain type of entry (user or peer), which of them are used for registration only and which are used for call authentication, which of them should be used in sections where devices for inbound call handling are defined and which of them should be used in sections where devices for outbound call handling are defined, etc. Does anybody know about such documentation?

By the way, I already have studied “Asterisk: The definitve guide” (well, at least the sections which I considered important for my case), but it didn’t answer these questions.

Thanks in advance for any help!