MMS
Multimedia Messaging System (MMS) is the logical evolution of the Short-Message System SMS, a text-only messaging system for mobile networks. MMS-enabled mobile phones enable subscribers to compose and send messages with one or more multimedia (digital photos, audio, video) parts. Mobile phones with built-in or attached cameras, or with built-in MP3 players are very likely to also have an MMS messaging client -- a software program that interacts with the mobile subscriber to compose, address, send, receive, and view MMS messages.
The MMS data flow starts with a subscriber using an MMS client on the mobile phone to compose, address, and send an MMS message to one or more recipients. MMS addresses can be either E.164 phone numbers (e.g., "+18005551212") or RFC 2822 e-mail addresses (e.g., "you@yourdomain.com").
The initial submission by an MMS client to the home MMSC (MMS Center) is accomplished using HTTP with specialized commands and encodings (which are defined in a technical standard specified by the . Upon reception of the MMS message, the recipient MMSC (MMS Center) sends a notification to the recipient's mobile phone using either an SMS notification or WAP Push.
There are two modes of delivery in MMS: immediate or deferred:
- immediate delivery: When the MMS client on the mobile phone receives the MMS notification, it then immediately (without user intervention or knowledge) retrieves the MMS message from the MMSC that sent the notification. After retrieval, the subscriber is alerted to the presence of a newly arrived MMS message.
- deferred delivery: The MMS client alerts the subscriber that an MMS message is available, and allows the subscriber to choose if and when to retrieve the MMS message. As with the MMS submission, the MMS retrieval request, whether immediate or deferred, occurs with an HTTP request. The MMSC responds by transmitting the MMS message in an HTTP response to the MMS client, after which the subscriber is finally alerted that the MMS message is available.
The essential difference between immediate and deferred delivery is that the former hides the network latencies from the subscriber, while the latter does not.
There are some interesting challenges with MMS that do not exist with SMS:
- content adaptation: multimedia content created by one brand of MMS phone may not be entirely compatible with the capabilities of the recipients' MMS phone. In the MMS architecture, the recipient MMSC is responsible for providing for content adaptation (e.g., image resizing, audio codec transcoding, etc.), if this feature is enabled by the mobile network operator. When content adaptation is supported by a network operator, its MMS subscribers enjoy compatibility with a larger network of MMS users than would otherwise be available.
- distribution lists: current MMS specifications do not include distribution lists nor methods by which large numbers of recipients can be conveniently addressed, particularly by content providers, called Value Added Service Providers (VASPs) in 3GPP. Since most SMSC vendors have adopted FTP as an ad-hoc method by which large distribution lists are transferred to the SMSC prior to being used in a bulk-messaging SMS submission, it is expected that MMSC vendors will also likely adopt FTP similarly.
- bulk messaging: The flow of peer-to-peer MMS messaging involves several over-the-air transactions that become inefficient when MMS is used to send messages to large numbers of subscribers, as is typically the case for VASPs. For example, when one MMS message is submitted to a very large number of recipients, it is possible to receive a 'delivery report' and 'read-reply report' for each and every recipient. Future MMS specification work is likely to optimize and reduce the transactional overhead for the bulk-messaging case.
MMS should not be confused with EMS, which is simply SMS with additional payload capabilties.
MMS has been deployed world-wide and across both GSM/GPRS and CDMA networks.
MMS was originally developed within the Third-Generation Partnership Program (3GPP), a standards organization focused on standards for the UMTS/GSM networks.
MMS has also been standardized within the Third-Generation Partnership Program 2 (3GPP2), a standards organization focused on specifications for the CDMA networks.
As with most 3GPP standards, the MMS standards have three stages:
- Stage 1 - Requirements
- Stage 2 - System Functions
- Stage 3 - Technical Realizations
Both 3GPP and 3GPP2 have delegated the development of the Stage 3 Technical Realizations to , a standards organization focused on specifications for the mobile wireless networks.
