The tech prefix setting can be found under the basic tab of your SIP Connections expert settings.
Why use a tech prefix?
You could have an IP phone system with many clients. Telnyx allows you to create multiple IP connections that share the same IP in order to segregate your clients traffic. All you need to do is apply a 4 digit tech prefix on each connection to differentiate your clients.
If you apply a tech prefix to a connection on your mission control portal account, make sure to prepend this to your outbound calls that you send to us.
Please note: if all your SIP Connections have a tech prefix but you don't send the calls to us with a configured tech prefix - calls will fail since we won't be able to identify the connection the call belongs to, so we will respond with a 407 Proxy Authentication.
What exactly is a tech prefix?
A tech prefix is a 4 digit prefix you append to the number you are dialing.
So the dialed number for a call with a tech prefix would look like 123418005678912
where the 1234 at the beginning is the tech prefix configured on the connection. You don't actually have to dial this before the number, most if not all phone systems are setup to be able to include a tech prefix for the outbound trunk used. So you should just need to set this up on your outbound settings and all calls will use the tech prefix.
Do you support tech prefixes at the number level settings?
Yes, please read this article which provides information on how to enable tech prefix settings on your numbers.