5 SIP Interview Questions and Tips (With Example Answers)

By Indeed Editorial Team

Published 6 May 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

If you're looking to pursue a career in IT or computer sciences, job interviewers may ask you about certain technical topics to assess your knowledge and competencies. One such topic for questioning may be session initiation protocols (SIPs). Learning some of the common SIP questions you may face can help you go into an interview feeling prepared and confident. In this article, we explore a selection of SIP interview questions with example answers and go through a few general interview tips to help you succeed.

5 common SIP interview questions, with example answers

Here are five common SIP interview questions interviewers may ask, with example answers:

1. Please define in your own words what SIP is.

Interviewers may ask a basic introductory question like this to assess your background knowledge. A straightforward question like this can also be a subtle way to ease you into the interview. Interviewers may also look to test your communication skills and measure your ability to articulate technical information. When answering, focus on concisely defining SIP, its importance and its functions. Consider using any relevant personal experience of its practical applications in your answer.

Example: 'SIP is an acronym for session initiation protocol and is a key component in internet communications. It's a text-encoded protocol that works with communication applications to initiate, maintain and terminate real-time sessions. SIPs provide signalling and control for all multimedia communication applications, including video conferencing, voice calls and instant messaging. SIPs create sequences of communication for participants in a session and define the format of messages exchanged. So, if you send a message to a group chat, the SIP allows you to initiate the application and send the message as it signals the operation of the messaging app.'

Related: 7 Best IT Certifications for a Successful IT Career

2. Can you tell me the difference between sessions, dialogs and transactions?

Interviewers may ask questions like this to assess your knowledge of industry-specific terms and content. Defining these terms within the context of the practical application of SIPs shows you have an in-depth, working knowledge of the subject. Being familiar with communicating using technical terms also indicates a level of professional competence. When answering, define each term before comparing them to each other to highlight how they differ in their role.

Example: 'All three are distinct aspects of media exchanges when using SIPs. A transaction is the fundamental element of message exchange and describes the request–response cycle. When two users initiate a session in a messaging application, the user-to-user relationship created is a dialog. Whenever a request has a non-failure response, an app creates a dialog. A session describes a media exchange between two or more endpoints, for example, if multiple users join a communication session in an app. It's possible for dialogs and sessions to function independently.'

3. What is the Call-ID header field, and why is it significant?

Interviewers may ask questions like this to assess your practical knowledge and experience. SIPs use several types of header fields, so they may ask you to define one to show you understand the differences between the types and their functional importance. When answering, define the Call-ID field and its function within the context of its role in SIPs. This shows that you haven't simply memorised a definition but understand the broader operation.

Example: 'When a user initiates a session, such as by calling another user, the SIP sends a signal called a SIP INVITE. An INVITE has several common header fields, one being the Call-ID field. This identifier allows applications to keep track of and distinguish sessions. The Call-ID generates a unique string to distinguish a session from others whenever a user starts a session. Users can then identify that session from others due to this unique, identifiable header.'

4. What is the Request URI?

This is another relatively basic question to help evaluate your understanding of key terms and technical knowledge. Interviewers may introduce another specific aspect of SIPs as a way of preparing for follow-up questions that require more in-depth thinking. Define the term and how Request URIs function, and think about areas they may ask you to elaborate on in subsequent questions.

Example: 'The Request URI is the method of identifying the correct users to call via SIP. A straightforward way to look at it would be as a user's SIP phone number. It's a string of characters denoting an identity. The format is similar to an email address, with 'sip:user@ host' being a common SIP URI format.'

5. What is the advantage of SIP URIs over IP addresses?

An interviewer might ask this to see how you can apply your knowledge. Here, you can show an understanding of the technical aspects, insight into practical functionality and an ability to use your knowledge and experience to make a critical evaluation. When giving your answer, define IP addresses and their functions in relation to SIPs and how the two differ. Then, in your evaluation, you could speak about the benefits of SIPs because of these differences.

Example: 'SIP URIs give a unique name to each user or session at the time of a message or call, and this name resolves to an IP address using both DNS lookups and SIP proxy servers. When routing requests, IP addresses only reach one device or endpoint. This makes them effective for one-way communication between different devices, but SIPs are far more suitable and functional for multimedia user communication. SIPs can work through multiple channels of communication. Since users may communicate through multiple channels or devices simultaneously, SIPs are more beneficial than IP addresses.'

Related: 10 Computer Science Careers (With Salaries and Duties)

General interview tips

Interviewers are doing more than evaluating your technical knowledge. The interview is also a chance for them to assess areas like how you may engage with other employees, how analytical you are by nature or how well you manage pressure situations. To make a positive impression during an interview, consider the following:

Research the company

Being able to demonstrate a knowledge of the company can be an excellent way to make a good impression. It shows that you're enthusiastic about the role. Taking the time to research the organisation can give you an insight into things like their culture and values. This can help you understand what sort of questions interviewers may ask and how you can formulate your answers. Researching the company can also help you think of intelligent, insightful questions you may wish to ask the interviewer when given the opportunity.

Review the job description

Reviewing the job advert and description gives you an idea of what the interviewer may ask. If you do this, the interview is likely to be less daunting. The job description may highlight key competencies and personality traits that the organisation is looking for from potential employees. Interviewers may structure their questions to see if you show these qualities. Think about your personal working experiences and how you can show the qualities highlighted in the job description to show that you're a suitable candidate.

Related: How to Write a Job Description in a Resume (With Examples)

Prepare but don't rehearse

As you get an idea of the questions, you may wish to prepare some answers. Such preparation may be beneficial but try to avoid rehearsing your exact answer. Recited responses in interviews may not give the impressions you wish them to. Rather than preparing and practising a scripted response, think about key points you want to make and the general structure of the answer. You can then fill in the rest depending on the specific question and how it's asked, keeping your responses natural and conversational.


Listening is important in an interview. Even if you know specific things you'd like to bring up and highlight, it's important to answer the question the interviewer has asked you rather than the question you might have wanted them to ask. Listen carefully to make sure your responses are relevant to the question. As you talk, interviewers may also give subtle indications of areas of your replies they find favourable. If you can recognise these positive reactions, you may highlight them in your responses.

Related: Active Listening Skills: Definition and Examples

Think about body language

Your body language can also say a lot about you. People may pick up on body language and other non-verbal cues and form opinions about you based on these. They may even make these opinions subconsciously. Be mindful of your body language and how you present yourself physically to make a good impression on an interviewer. Consider things like making eye contact and your posture when talking to people.

Explore more articles