Useful Knowledge Base resources for SIP

The Knowledge Base addresses all of our services. Here is an overview of resources that might be of interest for SIP users.

Key Concepts

Inbound and Outbound are frequently used words in the world of telecom. If you still have doubts regarding what lies behind these concepts, check out our dedicated article:
👉 Inbound vs. Outbound.

SIP is a constant balance act between bandwidth and call quality. To that end, codecs are your best allies for SIP, allowing for the reduction a the required bandwidth while preserving quality. To learn more about them, check our overview:
👉 Codecs Overview.

Channel is the term used to designate the maximum of simultaneous calls allowed on your account. To learn more about channels, such as how to add more, read our article:
👉 Channel Management.

Numbers and CLIs management

Be it for SMS or voice, SIP or SENDR, numbers are the heart of telecoms. We have written numerous pieces to help you understand all there is to know about them:

Here is an overview of numbers, sender IDs and CLIs and how to buy them on our platform:
👉 Numbers at CALLR

Numbers are of different types and length. Some types are consistent from one country to another; others are not. Get to know number types intimately with our dedicated content:
👉 Number Types Overview

Alphanumeric Sender ID allows you to display a string of characters as CLI. Its availability differs per country, check out our overview to know which country offers it:
👉 How to customize the CLI and sender ID?

You can port your existing phone number on our platform, and you can port out any number you bought using our services. Read our article to know how:
👉 Number Portability How-to

CDR and Call Status

We give you a vast amount of data on each call you produce using our platform to help you get all the insights you can from every communication. All this data is packed in the CDR, click below to know all there is to know about it:
👉 CDR Overview

You can track the result of every phone call you make with CALLR with: you'll know the precise reason for the success or failure of each communication you initiate. Check our dedicated content:
👉 Call Statuses

SIP Response codes are crucial to know what happens precisely with each call made on our platform. All the codes and their meaning are included in our reference:
👉 SIP Response Code Meaning

For each call, we provide you with the cause of the hang up using the ISDN cause codes. We regrouped all the codes and their meaning in the following article:
👉 ISDN Cause Code Meaning

Still have questions? Don't forget to check out our SIP FAQ.