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MSNP Protocol
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Microsoft Messenger for Mac

MSNP stands for "Microsoft Notification Protocol", the protocol used on MSN/Windows Live Messenger, all the way to when it was discontinued, and Skype's network used a heavily modified version of MSNP in the past. We not only will fully document the protocol, but will maintain and update it.

If you want to contribute, you can request an account by sending an email to with desired username and also a few words on what you have to contribute (for spam control). You should also check the Needed, which is a list of things we are looking for.

If you want to contribute something anonymously or without registering, send it to If anonymity is desired, state so, and your name/email will not be mentioned.

You can also donate to help with this MSN/Windows Live revival, because it is a full time job at this point.


Read additional frequently asked questions for clients and the Escargot service.

Protocol History

MSNP was first implemented with version 2 - MSNP2 - on July 17 1999. It only used TCP, no webservices or anything like that.

As time went along, MSNP was extended and improved upon, incrementing its version number. By MSNP8, a new authentication system: Passport. This was first time something essential was used that wasn't sent via the regular MSNP TCP socket.

From a technical standpoint the MD5 method that was used in MSNP7 was completely secure even from man in the middle attacks but Microsoft decided that it would be beneficial to MSN Messenger to authenticate directly with the passport servers, and Protocols/MSNP/Tweener was born.

After MSNP8, other, newer protocol versions were released (MSNP9, MSNP10, MSNP11, MSNP12, MSNP13 for WLM 8, et al). Most of the times the protocols introduced a more efficient way of storing contact lists and other properties, but also added new features as new clients were released to the public by the MSN Messenger team.

MSNP's final version was MSNP21, if we consider Windows Live Messenger 2012 the last version. However, MSNP22 existed, it was used on the Metro Messaging app on Windows 8.0, and MSNP24 was used on Skype for a while - although very different from regular old MSNP.


All connections to MSN servers take place over TCP/IP. The client always makes the outgoing connections to the servers. The official port for MSN Messenger is 1863, although there are many places in the protocol where alternate ports could be specified, so this may be subject to change.

The connection to the server must be considered asynchronous - you can send many commands to the server without waiting for a reply, and the server won't necessarily reply to your commands in the order you sent them. The server may also send messages that are not in reply to any particular message from the client. However, sometimes (for example, when logging into a notification server) the protocol requires you to send one command then receive one command, and so on.

There are also several OOB (out-of-band) protocols that take place directly between clients and do not involve the server. These protocols are described in their respective sections, and are not necessary for basic functionality of a client.


At the lowest level, computers can only send 1s and 0s to each other. In order for two computers to communicate, they must agree on what the 1s and 0s represent. In MSN Messenger (except in file transfer), they represent characters, such as "Latin Capital letter A", "Digital Four", or "Runic letter short-twig-sol". In other words, MSN Messenger is a text-based protocol.

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