SMS vs Voip messaging
This guide gives you a brief insight on what is the difference between the Short Message Service (SMS) used on mobile networks and VoIP messaging used mainly in office environments. In short we can state that both technologies are great. They have their weaknesses and strengths. In terms of popularity SMS is more popular then VoIP messaging.
What is SMS
Mobile telecommunication networks offer the option of transmitting short text messages between mobile terminals (mobile phones). This technology was developed to offer applications to terminal (mobile phone) messaging services which offer componies to send notifications automatically to users. If a componany would like to send notifications, they will likely setup an SMS gateway, and use it's built in SMPP Server or built in HTTP SMS API to pass messages to it for delivery.
What is SIP VoIP messaging
SIP messaging is used in Voice over IP (VoIP) networks. It is similar to SMS in the way that it is used to send text messages to terminals (desktop voip phones) that are capable of displaying these messages on their screens. SIP messaging is based on the the VoIP Info message extension of the SIP protocol and is supported by Ozeki VoIP SDK. With Ozeki VoIP SDK when you build a softphone or other VoIP application, you can send SIP instant messages and receive SIP instant messages with only a few lines of code. These messages will go through the SIP PBX the softphone is registered to. They will initiate a similar transaction used for call setup.
What is the difference between the two
The biggest difference between SIP messaging is SMS the users ability to create such messages. While mobile phones are equipped with great messaging apps, most VoIP devices are only able to display these text messages and don't offer any ways of input. This means that VoIP text messages are only sent by VoIP applications to notify users about various events (such as voicemail notifications, or service interruptions.)