[Troubleshooting] IBM Sametime Softphone: Error 404 User Not Found

If you are doing IBM Softphone integration with a third party SIP server like Polycom DMA, you could face that error: 404 User Not Found.

First of all, you have to read the document named "IBM Sametime 8.5.2 Unified Telephony Lite Client troubleshooting guide" (here). A good port configuration is important.
404 error can be cause by a misconfiguration of Virtual Hosts.
1/ Check the SIP ports configured on the application server and fix the VH settings accordingly (remove the redundant SIP ports, don't change/remove non-SIP ports)

1. sip_proxyreg_host VH should contain only SIP ports used by the P/R (it should NOT contain SIP ports used by the CF)
2. default_host VH should contain only SIP ports used by the CF (it should NOT contain the SIP ports used by the P/R) 

My port configuration on Media Manager:

In my configuration, VH for sip_proxyreg_host was like that:

I had to remove 5060 & 5061 lines, restart and retest your call from a SIP endpoint to a S9 client