Session Initiation Protocol (SIP) Auto Dialer | Difference Between SIP, VoIP & Twilio Auto Dialer

What is an SIP?

Session Initiation Protocol (SIP) is the protocol for initiating session calls. This protocol is designed to allow users to create, modify, and terminate multimedia sessions using the Internet Protocol. This is the application layer protocol that combines elements of the Hypertext Transfer Protocol (HTTP) and the Simple Mail Transfer Protocol (SMTP).

  • HTTP

HTML is a hypermedia document format which uses the Hypertext Transfer Protocol (HTTP) as the application layer. This protocol was originally designed to communicate between web browsers and web servers, but can also be used for other purposes.

  • SMTP

An application that is used to send, receive, and relay outgoing emails between senders and recipients is known as SMTP or Simple Mail Transfer Protocol. SMTP is used to transfer emails from one server to another over the internet. Emails sent through the SMTP server are known as SMTP emails.

VoIP Technology

Let us first understand a few points about VoIP before moving forward.

VOIP (Voice over Internet Protocol) allows you to deliver voice and multimedia (videos, pictures) over the Internet. Because the Internet is available anywhere and at any time, it is one of the cheapest methods of communication.

VOIP offers some advantages, including the following:

  • Cost-effective

  • Mobile compatibility

  • Extra cables are not necessary

  • A flexible approach

  • Meetings via videoconferencing

You must have access to an internet connection on your computer/laptop/mobile in order to make a VOIP call.

Who Are VoIP Providers?

Most traditionally, VoIP service providers have been seen as providers of VoIP Internet telephony services to residential and business customers. In addition to providing services and hardware to subscribers, VoIP service providers charge subscribers a monthly fee. VoIP providers transmit calls differently than traditional Public Switched Telephone Networks (PSTNs).

A VoIP provider uses packet-switched telephony to transmit calls over the Internet. Comparing it to circuit-switched telephony is good for understanding the differences between the two.

VoIP Provider Types

These three main categories of VoIP providers can be used to classify VoIP providers:

  1. Residential VoIP

  2. Business VoIP

  3. Wholesale VoIP

  • Residential VoIP

Voice-over-IP (VoIP) for the residential market is similar to traditional home phone services. It involves a preconfigured IP phone or adapter connecting to the internet for home phone services, as opposed to traditional home phone services using PSTN lines.

  • Business VoIP

Any kind of VoIP service offered by a business can be considered a Business VoIP service, including hosted PBX, On-Site PBX, or any other type of VoIP service.

  • Wholesale VoIP

Services such as wholesale DID buying, wholesale sip termination, or wholesale sip origination are provided by a wholesale Voip provider to services providers or customers.

How does the SIP Autodialer work?

SIP invitations have session descriptions that allow participants to agree on the media types that are compatible with their session. By using proxy servers, SIP routes requests to a user's current location, authenticates and authorizes users, and implements provider services call-routing policies. Users can access features through the site. Additionally, SIP allows users to upload their current location to be used by proxy servers via registration. The protocol is built on a variety of transport protocols.

Latency, packet loss, and Quality of Service (QoS)

VOIP implementations involve a major issue with QoS (Quality of Service), and we must take all precautions to ensure that packet traffic for voice will not be delayed or dropped due to disturbances from lower priority traffic.

Consider these factors:

  1. Latency

  2. Jitter

  3. Packet Loss


Delay for packet delivery, the time it takes for voice packets to travel from their source to their destination. The ITU-T G.114 specification recommends a maximum of 150 ms one-way delay


In the process of packet delivery, there can be variations in the delay. As voice packets are broadcast sequentially from the source, some packets take more time to reach their destinations due to the differences in the routes they travel. Jitter can be tolerated up to 50 milliseconds, as higher delays will negatively impact the quality of the service.

Packet Loss:

The default G.729 codec does not allow packet loss that exceeds 1 percent, because there is too much traffic on the network.

What is a SIP server?

This server is also called a SIP Proxy for handling all SIP related management in a network and responding to requests from user agents for placing and terminating calls. SIP servers are typically included in IP-PBXs that support SIP.

What is SIP in PBX?

VoIP services, such as SIP trunking, allow you to connect your existing PBX to the internet. Using this service, you can utilize your company's on-premise hardware PBX system. Generally, it has already been installed and is already being managed by your own IT staff. SIP trunks are direct connections between two premises systems: your PBX equipment and VoIP equipment.

SIP, Session initial protocol

SIP: - This protocol is the most widely used in the VoIP industry. SIP was developed by the IETF and has since become a de facto standard for VoIP applications. In SIP, signaling and data follow different routes as well as taking different routes for signaling and data.

Inter-Asterisk Exchange Protocol - IAX/IAX2 – is an option offered by Digium that uses both signaling and data on the same bus

A VoIP protocol that is supported by the ITU is H323.

Is SIP calling free?

A free softphone application is included with OnSIP for mobile phones and desktop computers. SIP applications that use standard SIP can be used with your free OnSIP account. Your SIP address can also be registered on any SIP-based desk phone for free voice and video calls.

SIP vs. VoIP: what's the difference?

An internet-based telephone service called VoIP, or Voice over Internet Protocol, allows voice conversations to take place over the Internet. The Session Initiation Protocol is an Internet communication protocol which allows for establishing and terminating VoIP calls, and sending audio and video messages on the Internet over computers and mobile devices.

Difference between SIP Auto Dialer & Twilio Auto Dialer?

A sip auto dialer is auto dialer that uses SIP protocol for dialing numbers

Twilio Auto Dialer is a type of Power Dialer that lets the user make calls to its customers to instantly dial the number without needing to do it manually. Auto Dialer can be integrated with your CRM system like SuiteCRM if you use the Twilio API to improve performance.

SIP stands for Session Initiation Protocol. An SIP Auto dialer is a protocol that provides services, SIP also known as a softphone dialer, Softphone dialer is a software program that is used to make calls over VoIP (Voice over Internet Protocol).

Is Twilio Auto Dialer a SIP Auto Dialer?

Yes, Twilio auto dialer supports SIP auto dialing under the Elastic SIP Trunking backend.

What is Elastic SIP Trunking?

Twilio's elastic SIP Trunking service scales automatically on-the-fly with unlimited capacity to meet almost any traffic demand. Using our self-service tools, you can deploy globally in just minutes without relying on slow providers. Twilio Elastic SIP Trunking gives you total control over your connectivity.

Final thoughts:

We discussed SIP auto dialer, VoIP Technology, its types and about Twilio auto dialer. As a result we get that (SIP) Sessions Initiation Protocol is a signaling protocol that initiates real-time voice, video, and messaging sessions. A Voice over Internet Protocol (VoIP) call consists of a voice communication session and multimedia session delivered over an Internet protocol network such as the Internet. Twilio Auto Dialer is a Power Dialer, allowing users to make phone calls to customers without having to manually dial their numbers.

By integrating Twilio API with your CRM (Customer Relationship Management) software such as SuiteCRM, you can enhance the performance of Auto Dialer. Twilio auto dialer is a SIP auto dialer by using Elastic SIP Trunking.