to their own customers or prospects when using their own gateway equipment. In Canada, SMS gateway providers are regulated by the Canadian Wireless Telecommunications Association (CWTA/txt.ca). In India, it is regulated by the Telecom Regulatory Authority of India (TRAI). In Pakistan, it is regulated by the Pakistan Telecommunication Authority(PTA). Direct-to-SMSC A direct-to-short message service centre (SMSC) gateway is a software application, or a component within a software application, that connects directly to a mobile operator's SMSC via the Internet or direct leased line connections. The Short Message Peer-to-Peer (SMPP) protocol is typically used to convey SMS between an application and the SMSC. Direct-to-SMSC gateways are used by SMS aggregators to provide SMS services to their clients and large businesses who can justify such use. They are typically employed for high volume messaging and require a contract directly with a mobile operator. Direct-to-SMS gateway An SMS gateway typically sits between the end-user who needs to send/receive SMS and a mobile network's SMSC. Such gateways provide their customers with a choice of protocols, including HTTP, SMTP, Short Message Peer-to-Peer and Web Services. Providers of SMS gateway services include SMS aggregators and mobile operators. SMS gateways are also available as part of messaging services such as AOL, ICQ and others. In order to send/receive messages with mobile subscribers, an SMS gateway connects with (i) mobile network SMSCs and/or (ii) other SMS gateways. It is, therefore, possible that an SMS gateway has a combination of connections with mobile network SMSCs and connections with other SMS gateways in order to provide its services. However, there is the increasing potential for delivery problems with SMS the greater the number of SMS gateways in the delivery chain. Email clients Text messages can be sent from a personal computer to mobile devices via an SMS gateway or Multimedia Messaging Service (MMS) gateway, using the most popular email client programs, such as Outlook, Thunderbird, and so on. The messages must be sent in ASCII "text-only" mode. If they are sent in HTML mode or using non-ASCII characters, they will most likely appear as nonsense on the recipient's mobile telephone. Before the message can be sent, one must determine the domain of the mobile carrier's SMS gateway. For example, if one wanted to send a message to a mobile telephone in the United States serviced by AT&T, and the telephone number is +1 415-123-4567, the email would be addressed as