Written by: Nick DiCiaccio, Biscom
Session Initiation Protocol (SIP) or H.323? Biscom offers an easy integration with both. The protocol you decide on in your network simply affects how your network will be managed.
“With today’s IP solutions, IT managers and CIOs often have the flexibility to decide on an IP
signaling protocol that fits into their environment. The two big ones out there today are SIP and H.323.”
When companies are considering moving to an IP communication solution to replace their legacy telecom infrastructure, an important point to think about is the protocol that the IP based phones, fax servers and video servers will use to transport the calls across the IP network. In the “old days”, this wasn’t much of a concern. You invested in a PBX, employees got phones at their desks, and those phones connected back to the PBX using either analog lines or digital extensions with pre-set protocols. With today’s IP solutions, IT managers and CIOs often have the flexibility to decide on an IP signaling protocol that fits into their environment.
The two big ones out there today are SIP and H.323.
SIP, or Session Initiation Protocol, is a text based protocol that sets up, manages and tears down IP sessions which transport real-time media.
SIP is used to set up:
- VoIP calls
- FoIP calls
- Video sessions
- Instant messaging
- And more
It is used not only in enterprise environments, but also as the de facto IP signaling protocol when companies opt for virtual IP trunks delivered to their sites to replace legacy technologies like ISDN. It was designed to be flexible, easy to learn, and simple to troubleshoot. More
and more of SIP is seen in enterprises and in carrier IP media solutions.
SIP is media-agnostic; it doesn’t care what the other side can do in terms of communicating. It leaves that part of the communication up to each device to work out. For added security, you can send SIP over Transport Layer Security so the signaling is encrypted. Using TLS, it’s then possible to encrypt the media using “Secure RTP”, so that both signaling and the media content is secure.
H.323, unlike SIP, is not one protocol but a grouped collection of protocols. Though essentially H.323 does what SIP does—sets up real-time media sessions over IP networks—it goes about it very differently.
H.323 uses one of its protocols to set up a basic connection, and another to open a logical channel to transport the media. Unlike SIP, H.323 plays a role in determining what types of media each side can support.
It’s based on ASN.1 syntax, not text, so it’s not as intuitive as SIP is to read and debug. With the continuing migration towards SIP based solutions, H.323 is slowly disappearing, though it
still has a heavy presence in companies as it’s the protocol that got there first.
Which protocol you decide on in your network affects how your network will be managed. Your IT group will need to know which ports to open on firewalls in your network, so IP signaling and media traffic is not blocked.
Default IP ports are 5060 for SIP and 1720 for H.323. Remember that the IP media will use different ports, usually port ranges blocked off in the higher numbers, e.g., 30000-39999. Also, IP signaling and media packets, as they’re working with real-time data, should be given a high
quality of service in your network—or better yet, transported over their own VLAN.
Whichever choice you make to set up a FAXCOM FoIP solution, Biscom supports both—SIP or H.323. Built on the Brooktrout SR140 FoIP license from Dialogic, FAXCOM delivers rock-solid
reliability whether you choose SIP or H.323 as your IP signaling protocol. Also, Dialogic has interop-tested many of the leading IP media gateways and SIP trunk providers as working smoothly with the SR140 license.
You can also visit us online at www.biscom.com.