Trying to get 3cx registered with an untested voip provider. Issue is that they require a tenant number in front of the SIP username for authorization. However, they want just the telephone number to show in the To/From sip header. Below is what i'm sending and is an example of what they want to see. The attached file ff2 is what i am sending. Everything here is correct except that in the highlighted area, I need to send 260010- in front of the telephone number. The file provider example is how they would like it to look. Any help would be appreciated.