Typical sip peer in mysql table ast_sipfriends_gs (system A):

*************************** 117. row ***************************
        _user_id: 134
            name: 6099
          secret: 5793439289
            type: friend
            host: dynamic
       defaultip: NULL
         context: from-internal-users
        callerid: Vorname Nachname <6099>
         mailbox: 6099
       callgroup: 1
     pickupgroup: 1
          setvar: __user_id=134;__user_name=6099
      call-limit: 20
subscribecontext: default
      regcontext: NULL
          ipaddr: NULL
            port: NULL
      regseconds: 0
        username: NULL
       regserver: NULL
     fullcontact: NULL
     accountcode: NULL
   allowtransfer: NULL
           allow: NULL
        amaflags: NULL
            auth: NULL
     autoframing: NULL
     callingpres: NULL
      cid_number: NULL
     defaultuser: NULL
        disallow: NULL
      fromdomain: NULL
        fromuser: NULL
   incominglimit: NULL
        insecure: NULL
        language: DE
          lastms: -1
  maxcallbitrate: NULL
       md5secret: NULL
      mohsuggest: NULL
      musicclass: NULL
   outboundproxy: NULL
         qualify: NULL
        regexten: NULL
  rtpholdtimeout: NULL
    rtpkeepalive: NULL
      rtptimeout: NULL
    subscribemwi: NULL
     usereqphone: NULL
         vmexten: NULL
       useragent: NULL

extconfig.conf (system A):

[settings]
sipusers      => mysql,asterisk,ast_sipfriends_gs
sippeers      => mysql,asterisk,ast_sipfriends_gs
voicemail     => mysql,asterisk,ast_voicemail
queues        => mysql,asterisk,ast_queues
queue_members => mysql,asterisk,ast_queue_members