Modify INVITE (to CMS Space / CMS Space naming)

I have spent serious time considering how I want to address my spaces within CMS. I’m personally not to happy with the idea to utilize prefix/suffix on the userpart, such as cmr-username, username.vmr – whatever name you want to use, or where you place it. My preferred logic there would be to have the CMS-spaces within a specific subdomain, so – to call a user directly you would dial username@domain.tld and to dial the space of the user you would dial username@meet.domain.tld.

Attempting to apply this logic does however introduce a few issues.

If the username should be used to provision the space – guess what, it will not synchronize that user. That causes a conflict with the adressing of the actual user if you were using the MeetingApp. Reachibility for the MeetingApp is way beyond the scope of this post, we are using devices and/or Jabber and will just use the spaces within CMS.

So, to manage this, I do need to provision the space using a prefix (or suffix), such as cmr-username and rewrite the invite on the way. Where should I do that? It would be very easily done in the VCS, a bit more tricky on the CUCM side – but still doable.

I will not argue that this script is perfect at the moment, but it is a start and can surely be developed further down the road. I’ve also argued heavily with myself if the To-header also should be updated, but it seems to work just fine with only updating the INVITE, so I’m happy with that for now.

The script;

M = {}

local cmrDomain = "meet.domain.tld" 

function M.outbound_INVITE(msg)
  local method, ruri, ver = msg:getRequestLine()
  if string.find(ruri, cmrDomain) then
    startTo_str = string.find(ruri, "sip:")
    endTo_str = string.find(ruri, "@", startTo_str+1)
    toUserPart_str = string.sub(ruri, startTo_str+4, endTo_str-1)
    if not string.sub(toUserPart_str, 0,3):match("cmr-") then
      changedToUserPart_str = "cmr-" .. toUserPart_str
      changedRuri_str = string.gsub(ruri, toUserPart_str, changedToUserPart_str)

return M

Worth mentioning about the script is the parameter for cmrDomain, without a check to make sure we are only applying this script for the actual domain we’re planning to use here – it would for sure break CUCM integration with regards to AdHoc conferences. (CUCM will create a temporary space, using id@fqdn – we don’t want to interfere there). Also, if you use another naming-convention then cmr-…., pay attention to line 11/12 and modify the code accordingly. There is also a check if cmr- is already present, if so we do not want to add it again.

Also, keep in mind – if you create dedicated spaces, configure them within CMS with the prefix of cmr-, or apply logic to exclude them from the script as well. 🙂

Modify Diversion history

I ran into a challenge with a customer after upgrade from CUCM 8.6 to 11.0 and Mitel CMG from 7.5 to 8.2.

They have a flow where a caller calls a CTI-Port which during opening hours has a CFUR to a hunt-pilot. The hunt-pilot has a CFNA/CFB to the CMG IVR.

The diversion history becomes quite interesting here;

Diversion: <sip:huntpilotno@10.x.y.z>;reason=no-answer;privacy=off;screen=yes,<sip:ctiportno@10.x.y.z>;reason=out-of-service;privacy=off;screen=yes

The issue that arises is that we will look at the first redirecting number (ctiportno), which – technically speaking, actually has a very correct reason (out-of-service). So, to be able to determine the cause for this forward after hitting the hunt-pilot, we would have to look at the last redirecting information – but, that is another number, and we will run into issues matching that to the subscriber in CMG.

In order to use the last redirecting cause, but still rely on the first redirecting number, I applied a LUA-script to the trunk.

M = {}
function M.outbound_INVITE(msg)
    local diversion= msg:getHeader("Diversion")
    if string.find(diversion, "reason=") then
      startDivCause_str = string.find(diversion, "reason=")
      endDivCause_str = string.find(diversion, ";", startDivCause_str+1)
      divCause_str = string.sub(diversion, startDivCause_str, endDivCause_str)
      changedDivCause_str = string.gsub(diversion, "reason=out%-of%-service;", divCause_str)
      msg:modifyHeader("Diversion", changedDivCause_str)

return M

This script will look if there is a reason within the Diversion and if so, search for the first occurrence (last redirecting pty) and then make a search and replace for reason=out-of-service with whatever the first reason is.

The diversion header in a call which does not get answered by the hunt will now look like this when hitting the CMG;

Diversion: <sip:huntpilotno@10.x.y.z>;reason=no-answer;privacy=off;screen=yes,<sip:ctiportno@10.x.y.z>;reason=no-answer;privacy=off;screen=yes

Some helpful resources;

NeTS failure on call from Jabber Softphone

NeTS version will not accept calls from Jabber in softphone-mode. Failure from NeTS is a bit cryptic;

|SIP           |SipNclaHandler::ExtractCallInfo          |D0828412 |<-- EXITING METHOD THROUGH NICEEXCEPTION:NICEEXCEPTION: 0XFFFFE052 INVALID SIP ADDRESS, SIPADDRESS=  ||SipNclaHandler.cpp|388
|SIP           |.x1_D0828412-csmState::UpdateContextFrom |         |<-- EXITING METHOD THROUGH NICEEXCEPTION:NICEEXCEPTION: 0XFFFFE052 INVALID SIP ADDRESS, SIPADDRESS=  ||SIPCallCtrlSM.cpp|947
|SIP           |csmsuper::HandleEvent                    |         |CAUGHT EXCEPTION HANDLING SIPREQUEST. NICEEXCEPTION: 0XFFFFE052 INVALID SIP ADDRESS, SIPADDRESS= ||SIPCallCtrlSM.cpp|585
|SIP           |TrProcessSipProviderMessage              |         |_COM_ERROR: _COM_ERROR: HRESULT: 0X80004003(INVALID POINTER  ), INVALID POINTER,  ||TrProcessSipProviderMessage.cpp|85

When comparing the SIP INVITE from a Jabber softphone and a 9951, the following difference was encountered in the header;

Contact: <sip:7009@10.x.y.z:5060;transport=tcp>;video;audio;+u.sip!"CSFMLUNDBOM";bfcp

The INVITE from the 9951 had only;

Contact: <sip:7009@10.x.y.z:5060;transport=tcp>;video;audio

Most likely, the +-sign is not interpreted correctly. The easy workaround here is to utilize the SIP-normalization rules and clean up the Contact-header (I can’t see any cases where this information would be relevant for NeTS).

Within CCMAdmin, go to Device, Device Settings and SIP Normalization Script. Click Add New. Give it a name, description and enter the following in Content;

M = {}
function M.outbound_INVITE(msg)
    local contact = msg:getHeader("Contact")
    local uri = string.match(contact, "(<.+>)")
    msg:modifyHeader("Contact", uri)

return M

Apply the script to your SIP-trunk heading to NeTS;


..and reset the trunk.

The result here is that regardless what extra flags is present in your Contact-header, only the content included within <> is sent over the trunk.

With this workaround, NeTS accepted the Jabber calls without issues.