SMPP - Protocol to send/receive Application SMS

What is SMPP

SMPP is a Protocol which allows non-mobile entities(i.e. which are not on radio connectivity) to use services of Operator SMSC for sending or receiving sms.These non-mobile entities can be VAS(Value Added Service) Provider or can be a website which offers web sms facility or can be a bulk sms provider and there can be many more seekers and users of SMS sending facility.
When i say "Receive SMS" then it is mostly of interest of VAS providers which get all sms sent on any VAS number(say 12345) by its subscribers.It then processes those sms according to service request and respond to subscriber.This service request can be ringtone download, voting or any other sevice as offered by VAS Provider.

References/Specifications

Following links have more information related to specification(or as an reference) for SMPP :

http://en.wikipedia.org/wiki/Short_message_peer-to-peer_protocol
http://www.smsforum.net/SMPP_v3_4_Issue1_2.zip
http://www.answers.com/SMPP

How to get a SMPP Account
As mobile Operator is wholesole owner of its SMS Property(Read my post Short Message Services & Mobile Operators) , So Normally following rules are followed to get a SMPP account directly from operator :

1. If you are a VAS Provider, then your service should have some differentiating factor. It should also commit minimum number of SMS from subscriber base and should also provide minimum guarantee amount to cover low hits.

This domain of VAS on sms has very well set players since years and operators hardly now allocate new SMS VAS code to new players. Exception are new TV channels or media houses which either bring more users or hefty service amount.

2. If you are a Bulk SMS provider or website offering SMS facility or some Bank who is interested for SMS servcies, then they need to meet minimum traffic count(which is normally in millions) for a month. At the same time, it should ensure that no spam or fake sender sms would go through this account.

As i mentioned in my previous post(), Now a days SMS Aggregator is the Boss. He can provide you SMPP account at much lesser traffic requirements but at somewhat higher per sms rate.

SMPP Account of SMS Aggregators
SMS aggregator takes one or more SMPP account from opertor as big pipe. He puts up his SMPP server at any data centre or high connectivity location. This SMPP server caters to the need of many small pipes of different small SMS user accounts. It combines traffic of all such accounts and submits to operator in backend using big SMPP pipe(It acts as SMPP client in this case).In other words, it collates SMS traffic on standrad SMPP interface acting as SMPP Server and forward/relay the same to Operator SMSC acting as SMPP Client. Delivery reports are submitted using reverse path.

Following is list of few known aggregators which offer SMPP Account :

http://www.clickatell.com/developers/api_smpp.php
http://www.routesms.com/product.asp

There would be many more, but these are the two who have presented it well and are known long term players in messaging business.

Please note that SMPP is considered to be specialized protocol/interface and you must havae technical knowledge or technical staff to take care of Day-to-Day issues related to the same.

SMPP Client
Why to reinvent the wheel ? You want to setup SMPP account account fast and get started. Where can you find SMPP Client (for sure , at no cost or at minimal cost)? Following is the list of SMPP Clients which are mostly in use and available as opensource :

1. Kannel is Linux based SMPP ciient which is mostly used for SMPP connectivity with mobile operator. It offers very good features as required for SMPP Client or as WAP Gateway. More details can be found at http://www.kannel.org/

2. Logica offers API and some sample programs for testing SMPP connectivity. Its ready to use for testing but requires some programming efforts to make it seamless SMPP Client. Following is quick link for the same :
http://opensmpp.logica.com/CommonPart/Introduction/Introduction.htm

3. NowSMS provides excellent web based interface for message submission with SMPP in backend. It provides excellent utilities for sending various types of messages through SMPP interface covering OTA settings, unicode, ringtones and various other types of messages.But features come at a cost, its not free but a commercial tool. Though it provides evaluation version for 30 days.
http://www.nowsms.com

Buzz me a mail at sms.dreams@yahoo.com if you need my professional services to get your SMPP connection up and running with any SMPP gateway.

Common Problems with SMPP
1. Normally, SMPP Client face issue due to network connectivity due to which connection is aborted. Other issue is socket corruption. In both cases, SMPP Client should have feature of auto-discovery of these exception events and should have facility of auto-connect.

2. Some permutation/combination are required if some special message support is desired in SMPP Client. Its implementation vary from one SMPP Server implementation to other.I would cover more for SMPP character set in another post.

3. Throughput is better if separate connection for messgae sending and receving delivery reports is maintained.i.e. two connections with Tx and Rx mode individually than single connection with TRx mode.

Other variants of SMPP
There are various other variants of SMPP which is being used for things other than messaging. Following are few of these :
1. ZTE provides prepaid charging API for IN using a Protocol called SMPP+(SMPP plus) which is extension of SMPP with addition of some non-standard message types.

2. USSD gateways normally provide SMPP interface for transferring application logic to external content providers.