I am just wondering if i could upgrade the IOS on a CTS1000 without Call Manager? Is it possible to just use a TFTP server and upload the new IOS onto the codec with no CM?
That would depend on what version of CTS code your endpoint is running.
Earlier versions of CTS allowed you to upgrade the codec locally over HTTP, but that hasn't been an option for quite some time.
More than likely you wouldn't be able to upgrade that endpoint without CUCM.
Unless you could somehow point the unit at a server that sent it a properly formatted configuration file that directed it to an alternative TFTP site that had the right version of code you wanted, similar to specifying an alternate TFTP for a phone.
You may want to try creating a CUCM instance in a Virtual Machine and carrying that around with you on a laptop for just such an occasion.
I've used that solution several times to resolve issues with CUCM servers that were a long distance away from the site I was building.
I thought you received a free copy of CUCM with every CTS units..you could simply install it on vmware like suggested or on a spare server if you have one..its kinda risky to upgrade codec through any other means than CUCM, since you could easily brick the codec if the upgrade fails.
Just for the record, for newer CTS versions, we can get root access setup a TFTP and perform the upgrade from there, this will require of course root access and...later a CUCM to register...hence we will be back to square 1,