Reference section - SMPP
enquire_link
SMPP enquire_link
4.1.2 Enquire Link Operation
This PDU can be originated by either the ESME or MC and is used to provide a confidence check of the communication path between an ESME and a MC. On receipt of this request the receiving party should respond with an enquire_link_resp, thus verifying that the application level connection between the MC and the ESME is functioning. The ESME may also respond by sending any valid SMPP primitive.
The enquire_link can be sent when the session is in the open, bound (TX, RX or TRX), unbound or outbound states. Typical values for the period of inactivity before the ESME or MC originate this operation are between 30s and 120s.
4.1.2.1 enquire_link Syntax
| Field Name | Size Octets | Type | Description | Ref. |
| command_length | 4 | Integer | Defines the overall length of the PDU. | 4.7.4 |
| command_id | 4 | Integer | 0x00000015 | 4.7.5 |
| command_status | 4 | Integer | 0x00000000 | 4.7.6 |
| sequence_number | 4 | Integer | Set to a unique sequence number. The associated enquire_link_resp PDU should echo the same sequence number. | 4.7.24 |
4.1.2.2 enquire_link_resp Syntax
The enquire_link_resp PDU is used to reply to an enquire_link request.
| Field Name | Size Octets | Type | Description | Ref. |
|---|---|---|---|---|
| command_length | 4 | Integer | Defines the overall length of the PDU. | 4.7.4 |
| command_id | 4 | Integer | 0x80000015 | 4.7.5 |
| command_status | 4 | Integer | 0x00000000 | 4.7.6 |
| sequence_number | 4 | Integer | Set to the same sequence number of original enquire_link PDU. | 4.7.24 |
SMPP Analyser
The SMPP Analyser acts as an SMPP proxy, with the client application binding to the service and the service onward binding to the SMSC or SMS Gateway. Packet captures can be viewed in your browser or exported into Wireshark. Use the online SMPP Analyser >
SMSC Simulator
Looking to test your SMS application or SMS-enabled application before connecting to a live SMS gateway or SMSC? Our SMSC Simulator service allows you to test using the SMPP protocol v3.3, v3.4 and v5. Read more about SMSC Simulator >
SMPP Client
Test an SMPP account and service using the Melrose Labs SMPP Client . Use from your web browser. No software installation necessary.