Technical

Interface Protocol

The SMSCarrier service supports the Short Message Peer to Peer (SMPP) protocol v3.3 and v3.4 and the Hypertext Transfer (HTTP) protocol. Technical information regarding each of the protocols, including the specific subset of capability supported which is contained in the SMSCarrier Abbreviated SMPP Protocol Implementation Conformance Statement (PICS), are available below.

Originator Addressing (Source Addresses)

Two types of account are available under the SMSCarrier service: the Prime account and the Dynamic account.

For the Dynamic account control of the source address is provided and source addresses do not have to be pre-registered. Note that premium rate voice telephone numbers are not permitted to be used.

For the Prime account all source addresses that are required to be used for MT SMS must be registered with the service prior to use. There is no fee associated with registering such addresses. Only alphanumeric source addresses, or "abbreviated MSISDNs" allocated by SMSCarrier, are permitted.

Timestamp Localization

The timestamp on SMS sent through SMSCarrier can be localized based on destination mobile telephone. HSL's SMSCs are located in the UK but the timestamp of SMS sent through the service can reflect the mobile user's local time to assist with user experience. Timestamp correction is optional and is available on a subset of networks supported by the SMSCarrier.

Delivery Infrastructure

The SMSCarrier service utilizes the advanced technical messaging infrastructure of HSL including SMSCs owned and operated by HSL and the SMSCs of networks with which HSL has a commercial agreement for the delivery of SMS. Messages submitted through the SMSCarrier service are routed directly via HSL to an SMSC and sent from that SMSC over its SS7 interface to be delivered to the destination network. In the case of all networks included in the SMSCarrier service there is no more than one degree of separation between the customers of the SMSCarrier service and the SS7 network in order to provide a high quality of service. Mobile Number Portability (MNP) is supported to ensure messages are delivered to ported numbers.

In order to reliably deliver SMS messages, Short Message Service Centres (SMSCs) are used to convey messages between mobile users, and between mobile users and applications. HSL utilize a large number of highly reliable SMSC platforms from established mobile operators and HSL's own carrier grade SS7 SMSCs as part of their delivery infrastructure for inbound and outbound messaging. HSL's delivery infrastructure comprises mobile operator SMSC platforms located on their own networks and also HSL's own SMSCs located on an established mobile network. Key elements of our infrastructure also include the data centre sites, and the links between sites, SMSCs and networks.

HSL's SMSCs (Short Message Service Centres)

The introduction of HSL's own SMSCs, to compliment their existing SMSC connections with established mobile operators, provides exciting service opportunities for HSL and their clients. As with all core messaging software systems operated by HSL, the SMSCs are the result of internal software development by HSL’s software engineering team, with development having commenced in 2000. The currently deployed SMSCs located in the United Kingdom on HSL’s SS7 network are connected to the global SS7 network, of which the first SMSC went fully live in October 2004.

HSL’s SMSCs comprise integrated HLR (Home Location Register) and MSC (Mobile Switching Centre) capability and have a high degree of functionality for inbound and outbound (MO/MT) SMS. SMSC platforms communicate directly with the SS7 network to provide low latency, highly reliable means of SMS delivery.

HSL have introduced further SMSC platforms into service during 2005 and 2006, on a shared and dedicated basis, and plan to increase service offerings to clients based on these platforms.

HSL Data Centres / POPs

The SMSCarrier service operated by HSL is provided using HSL's own server infrastructure located at three geographically separate and independent sites located in the UK and the USA. These points of presence (POPs) allow customer access to our network infrastructure. The infrastructure is designed to allow for a failure of a site and for service availability to be unaffected.

Physical Security: Sites operate a strict security policy where site monitoring and access controls are in place. Access to service infrastructure and controls is restricted to qualified and authorized engineers.

Power Supplies: The Edinburgh Gyle (UK) site has dual independent 11kV feeds, backed up by dual battery string Chloride UPS systems and Cummins 1.4 Megawatt and 0.8 Megawatt diesel generator sets which are tested on a monthly basis. The Livingston (UK) site utilizes an array of APC UPS systems and has recently been upgraded to increase supply duration in the event of power failure.

Environmental Control: Fully redundant air handling units provide a constant fresh airflow. The air handling units vary the air temperature in order to match power dissipation.

Traffic Handling: In normal operation all sites dynamically share SMSC connections and load balance customer traffic over all suitable service SMSCs. In the event of an interruption to connectivity between sites, each site automatically operates independently and handles traffic without any impact to customer service.

Connectivity: Each site utilizes different ISPs for providing access to the Internet. Our Livingston (UK) site is served by a resilient connection via multiple links to different core routers at the serving ISP. Our Edinburgh Gyle (UK) site is served directly by a LAN connection to a different serving ISP.

The SMSCarrier service is operated in such a way as to ensure that customers ALWAYS have access to the service and that overall service availability is 100%.