SDK 6.7.5 is the latest Brooktrout development kit providing feature rich capabilities to our partners.  We’ve added some new features that will be quite useful, and I will discuss a couple of them on what they do and why they can help you.

A second change we made in SDK 6.7.5 is a format change for the sip_Contact field in the callctrl.cfg file.  As the name implies, this field sets the SIP Contact field in the SR140’s outgoing SIP INVITE message when it places an outbound call.

This new change will allow sip_Contact to have a format of ””.  Previous to this change, the sip_Contact field could only be an IP address, no “name” part at all.  If you use the Brooktrout Configuration tool to set sip_Contact, it will now show an open string to enter the information rather than being broken up into four sections (one for each IP address digit) as before.


We made this change because we’ve seen examples where SIP registration servers, especially those out in the cloud, need to have the SIP Contact in this format.  Without this change, you’d have to have a firewall or session border controller (SBC) or something like that change the SIP Contact format for you so the registration server likes it.

Note that the IP address part of the sip_Contact field can only have the internal IP address of the system (shown by ipconfig on Windows or ifconfig on Linux).  That has not changed here.  So if your machine is behind a firewall, you can’t set sip_Contact to an external address.  Doing so would cause errors when you tried to dial out from the SR140.  The SR140’s SIP stack only knows about the internal address so that’s the one that needs to be used.

This picture of a Wireshark trace shows an example of the new format: