MOBITEK® STK (SIM Application Toolkit) API

Application Programming Interface

STK-sim cards-1

Accessing the SIM Application residing in the SIM card is no longer limited to hand phone. With MOBITEK®SIM Tool Kit Application Programming Interface (STK API), Windows application can now access the SIM application.

(Note: STK, SIM Tool Kit, SIM Application Tool Kit, and SIM Toolkit are used interchangeably)


MOBITEK®STK API allows system integrator, or software developer (SI/SD) to develop their own user interface, or software application that can access to, and interact with SIM Application.

MOBITEK® STK API can be used to build a pre-paid account reload or recharge system. It supports reload via:-

  1. STK
  2. USSD
  3. SMS

MOBITEK® STK API is free with purchase of MOBITEK® Q24 STK Modem Hub.


Data Sheet



To Order

To get MOBITEK® STK API, order MOBITEK® Q24 STK Modem Hub or  contact us.

Technical Specification

  1. API TYPE: ActiveX DLL component (Component Object Model) for Windows
  2. ActiveX Name: MobitekSTK6.dll
  3. Version: 6.5
  4. The API contains 5 classes:
    1. Modem
    2. SIMToolKit – SIM Tool Kit
    3. SMS – Short Message Service
    4. USSD – Unstructured Supplementary Service Data
      • New function is USSD.USSDListen()
        This function call will listen for USSD prompt from the network operator and capture it. While listening, no other functions are allowed to be called, it will stop upon time-out (default is 3 seconds). If USSDListen() is not called, any USSD prompt is sent by network operator, then it will not be captured. If USSDListen() is called after USSD prompt is sent by network operator, then it will not be captured.  This allow software developer to wait for a response or prompt from GSM network operator that is transmitted via USSD.
    5. Phonebook
  5. Manual for Software Developer: refer to STK API Manual
  6. Sample codes for version 6.5:


List of SIM Cards

MOBITEK®STK API had successfully tested with the following SIM card and SIM application. To view demonstration, please click on these links:-

GSM Network Operator Country STK Menu
Maxis Malaysia E-Load
Digi Malaysia Flexi E-Load
SMART Philippines eLoad
Globe Philippines
Sun Philippines
Grameenphone Bangladesh ERS
Safaricom Kenya m-Pesa
TataDOCOMO India
BSNL India
Airtel India
Mobilnil Egypt
Viettel Vietnam


Success Story

We like to share a success story of our client, One & Only System (Pvt) Limited, Sri Lanka, who used our technology — MOBITEK® STK API and MOBITEK® Q24 STK Modem Hub to build a air-time reload system for their service called — “PayTM”

List of Customers

    • One & Only enter the era of direct cash payment through ATMs on October 15 which will start operating in Colombo for the first time. ‘PayTM’ machine in their two models ‘Smart Fiony’ and ‘Elegan Fiony’ accept various Sri Lankan currency notes and it work fast and efficiency.
    • Topup4you: an internet based global service for Bangladeshi citizens living abroad. Our service provides easy and prompt way of flexi/ Topup/easy load to Bangladeshi mobile numbers from anywhere of the world. A person who desires to recharge talk-time to mobile numbers of his or her loved ones in Bangladesh can do it very easily using our system. This is a 24×7 global service being internationally reviewed and used in 39 countries.
    • List of GSM Operators Supported:-
        1. Grameenphone (Grameenphone Ltd.)
        2. Banglalink (Orascom Telecom Bangladesh Limited)
        3. Robi (Axiata (Bangladesh) Limited)
        4. Warid (Warid Telecom International Ltd.)
    • SSL Wireless
    • ValuePLUS Computer Systems Ltd.
    • CEMET Ltd.
    • Aristotle Ucab
    • VietPay eCommerce service JSC (
  6. INDIA
    • Nomadic Solution Pvt Ltd
  7. KENYA
    • Web Tribe Ltd
    • PayPoint Solutions Limited
    • Gabriel Wamunyu
    • CredTran
    • Symtel (
    • Mobile Rechargespot Limited
  10. JORDAN
    • Abdul Rahman Alrbee
    • AIM Group
    • Selcom Wireless Limited
  12. UGANDA
    • Beyonic Technologies
  13. AFRICA
    • Brown Shomari Rashid
    • Zoona

Mobile Application – Reload Menu

Souce Code is FREE!

We understand that in air-time reload, top-up or recharge business you have a lot of agents sending reload command via SMS to your SMS Gateway that uses MOBITEKTM Q24 STK Modem and MOBITEKTM STK API.

Sometimes, the agents will make mistake when composing SMS command, e.g.:-

  1. typing wrong code for GSM network operator;
  2. typing the wrong code for the top-up amount;
  3. typing the wrong sequence for the command ;
  4. typing the wrong number of the SMS Gateway or Reload Gateway the above mistakes will cause delay in transaction; time and money is wasted (for sending wrong SMS and need to reply error code to agent).

We have a solution for you a mobile application that runs on Nokia — Air-Time Reload Menu. The menu will be installed on agent’s Nokia mobile phone. By using the menu, agent need only to perform this tasks:-

  1. select the GSM operator;
  2. select amount to be reloaded;
  3. enter the customer’s mobile number;
  4. enter the PIN

Thereafter, SMS will be correctly composed at the right sequence, and automatically send to your SMS Gateway or Reload Gateway.

Good news! The source code will be free to licencee of MOBITEKTM STK API (subject to terms and condtions). Please contact us to become our licencee and to get free source code.

Specification of the Mobile Application – Reload Menu

  1. Platform: Symbian OS, S60 3d edtion and 5th edition
  2. Langauge: Python
  3. List Mobile Phone Models Supported:-
    1. Nokia E series, e.g. E71, E72, etc.
    2. Nokia N series, e.g. N97, etc.

Presentation of the Reload Menu


Reload Menu S1-1

The 1st screen will be a menu listing the GSM operators in your country. The illustration on left lists all operators in Malaysia

We are able to customised to list all operators in your country.


Reload Menu S2-1

Once the operator is selected, the 2nd screen will be a menu listing the reload amount.

The illustration lists the currency in Ringgit Malaysia, we are able to customised according to your currency


Reload Menu S3-1

Reload Menu S4-1

Once reload amount is selected, the 3rd screen will ask for the customer’s mobile number whose prepaid account will be reloaded.


Reload Menu S5-1

Reload Menu S6-1

Once the number is entered, the 4th screen will request for the PIN of your agent, dealer or reseller that uses your air-time reload system.


Reload Menu S7-1

Once PIN is entered, the 5th screen will ask for confirmation that SMS with message “HHHH DC100 016334488” will be send to your Reload Gateway. The number of the Reload Gateway is “hard-coded”, i.e. the number cannot be changed by the agent, dealer or reseller.

The SMS is automatically composed based on the item selected in the menu or value entered. The format is
<PIN><space><GSM operator><amount><space><mobile number>

We can customised the format according to your system, e.g.
<GSM operator><space><amount><space><mobile number><space><PIN> ; or
<mobile number><space><GSM operator><space><amount><space><PIN>

For licencing enquiry, please contact us.

To Order

To get MOBITEK® STK API, order MOBITEK® Q24 STK Modem Hub or  contact us.


Change Log