SIP Instant Messaging: Team Chat in a Softphone
Tom Reed · Updated 10 November 2026
SIP instant messaging uses the SIP MESSAGE method to send text between SIP users, so colleagues can chat in the same softphone they use for calls. In a business softphone it covers one-to-one chat, group chat rooms, file sharing and read receipts, with history synced across devices. It's team chat, not SMS to phone numbers.
This guide is for small teams and the IT admins who set up their phones. It explains SIP messaging in plain words, what team chat gives you inside the app, how it differs from SMS, and what you need in place before you roll it out. It keeps to generic steps, because the exact screens depend on the app release and your account.
What is SIP instant messaging?
SIP instant messaging is a text message sent over the same SIP account that handles your calls. The SIP MESSAGE method is the part of the SIP standard that carries those short messages, so a softphone that supports it can send and receive chat without a separate account for a separate chat tool.
For a team, the point is simple. One login gets you calls, video and chat. Nobody has to keep a second app open, remember a second password or ask IT to add them to a second system. If you are choosing an app for this, look at business softphone apps with chat, group chat and SMS, which work with SIP-based PBXs.
What can you do with team chat in a softphone?
Team chat in a business softphone covers the things people use a chat tool for every day. In SessionTalk softphones that includes:
- One-to-one chat between colleagues, with delivery and read receipts so you can see a message has arrived.
- Group chat rooms, with room invitations, occupant management and persistent message history.
- File and image sharing, with thumbnails for images and documents. Every file transfer is encrypted end to end with per-message keys.
- Emoji reactions to any message.
- Typing indicators, so you can see when someone is replying.
- Synced history, so a conversation started on your phone carries on from your desktop.
See softphone messaging features for the full list. Which options you see depends on the app release, your account configuration and your service.
Is SIP messaging the same as SMS?
No. They look alike on a screen, but they are different things. SIP team chat is between colleagues on your chat service. SMS and MMS reach any phone number, and they need a separate connection to a messaging provider. A provider connection does not turn a conversation with a customer into a team chat room.
| SIP team chat (SIP MESSAGE) | SMS / MMS | |
|---|---|---|
| Who you reach | Colleagues on your chat service | Any phone number |
| What it needs | A configured chat service | A separate SMS/MMS provider connection |
| Group chat rooms | Yes, with invites and persistent history | No team rooms |
| Files and reactions | Files, images, emoji reactions, typing indicators | Depends on the provider (MMS for media) |
| Best for | Internal coordination around calls | Customers and contacts outside the team |
Use team chat for the quick internal questions that surround calls, and SMS for customers who prefer a text. If your contact centre also handles messaging channels, SMS and WhatsApp for an omnichannel contact centre covers that side.
When does chat inside the softphone beat a separate chat app?
Chat in the softphone earns its place when the question is about a call. A few examples:
- Reception and transfers. Reception asks "can you take this call?" in chat before sending it on. That fits well with a warm handoff, which attended vs blind transfer on a softphone explains.
- Field staff on mobile. People who are out of the office get chat and calls in the one app on their phone, with the same history they see at their desk.
- Support teams. A colleague can drop a screenshot or document into a chat room while another is on a call with the customer.
- One app to roll out and secure. You provision and support one app, not a calling app plus a chat app.
Before you ping someone, check whether they are free. Presence shows Online, Away, Busy, Do Not Disturb or On The Phone. If you want the PBX side of presence, read presence and team chat on a phone system.
What do you need to set it up?
You need a few things in place, and none of them is complicated. Team chat needs a configured chat service. Each user needs an account provisioned to them, and QR code provisioning is covered on the softphones page. Then install the apps on the devices your team uses: iOS, Android, Windows and macOS. Check the setup guide for your connection, because the available messaging options depend on the app release, your account configuration and your service.
Run through the checklist below before go-live. It is short, and the last item is the easiest to skip: test with two real devices before anyone depends on it.
Pair it with a hosted PBX
Pair it with a hosted PBX so calls, extensions and transfers sit on one system while your team chats in the same app. Your PBX handles the calls, extensions and transfers, and the softphone gives each person chat, video and calling in one place, so there is one thing to learn and one thing to support.
Rolling out softphone chat: checklist
- Chat service configured for your SIP accounts
- Users provisioned (QR code or your provisioning method)
- Apps installed on the devices your team uses (iOS, Android, Windows, macOS)
- Chat rooms created for teams or shifts, with the right members invited
- Agree what goes in chat, what goes in a call, and what goes by SMS to customers
- Decide whether you also need provider SMS/MMS (a separate connection)
- Test chat, file sharing and read receipts between two devices before go-live
FAQ
What is SIP MESSAGE?
SIP MESSAGE is the SIP method for sending instant text messages between SIP users. A softphone uses it to carry chat over the same account as your calls, so colleagues can message each other from the app without a separate chat tool and without leaving the call screen.
Can I chat with a group in a softphone?
Yes, with group chat rooms. You invite members, manage who is in the room, and keep a persistent message history, so a new joiner can see what was said. Rooms work well for a team, a shift or a project that needs a standing conversation next to its calls.
Is softphone team chat the same as SMS?
No. Team chat is between colleagues on a chat service. SMS and MMS to phone numbers are a separate connection to a messaging provider, and they do not turn a carrier conversation into a team chat room. Keep chat for the team and SMS for customers.
Does chat history sync across devices?
Yes. Full message history syncs across your devices, so you can start a conversation on your phone and carry on from your desktop without losing the thread. The options you see can depend on the app release, your account configuration and the service you have.
Can I share files in softphone chat?
Yes. You can share images and documents, and they appear with thumbnails in the conversation. Every file transfer is encrypted end to end with per-message keys. Pair that with read receipts to confirm a colleague has seen what you sent before you move on.
