# SMPP connectivity

Sinch supports [TLS encryption](https://community.sinch.com/t5/Glossary/TLS/ta-p/7757) to ensure secure connectivity to the SMPP servers. As most client SDKs for SMPP do not natively support TLS integrations, you may need a tunnel solution to configure a secure connection between your client and our server.

## SMPP account details

An SMPP account consists of a regional `host` connected to TLS port 3601, a `system_id`, and a `password` to consume our services. Be sure to use the correct region for your host.

| Account detail | Input |
|  --- | --- |
| Hosts | Host URLs take the form of `<region>.smpp.sinch.com`. For a list of hosts and regions, see the [Hosts](#hosts) section and table. |
| Port | TLS port 3601 |
| System ID | `system-id` |
| Password | `password` |


By default, only two parallel connections per `host`/`system_id` combination are allowed. If your application requires more parallel connections, please reach out to your [account manager](https://dashboard.sinch.com/dashboard).

### Hosts

The table below details the hosts, their corresponding URL, and the corresponding location. Customer Data will be stored in the corresponding locations listed below.

| Hosts | URL | Location |
|  --- | --- | --- |
| US | `us.smpp.api.sinch.com` | USA |
| EU | `eu.smpp.api.sinch.com` | Ireland, Sweden |
| Australia | `au.smpp.api.sinch.com` | Australia |
| Brazil | `br.smpp.api.sinch.com` | Brazil |
| Canada | `ca.smpp.api.sinch.com` | Canada |


Please note that:

- Sinch uses systems, customer service teams, development teams and service providers located within production server locations and overseas, whom may have access to and process Customer Data.
- Personal Data will be processed in accordance with the [Data Protection Agreement](https://www.sinch.com/data-protection-agreement/) and include the use of sub-processors for the services as described on the [Sub-Processors page](https://www.sinch.com/data-protection-agreement/sub-processors/).


## IP access

Access to the Sinch SMPP servers is by default restricted to pre-registered IPs. The client IP range must be announced and added to the client account for access.

## Supported SMP PDUs

| SMPP PDU from client | SMPP PDU from server |
|  --- | --- |
| `bind_transmitter` | `bind_transmitter_resp` |
| `bind_receiver` / `bind_receiver_resp` | `bind_receiver_resp` |
| `bind_transceiver` / `bind_transceiver_resp` | `bind_transceiver_resp` |
| `enquire_link` / `enquire_link_resp` | `enquire_link` / `enquire_link_resp` |
| `unbind` / `unbind_resp` | `unbind` / `unbind_resp` |
| `submit_sm` | `submit_sm_resp` |
| `data_sm` / `data_sm_resp` |  |
| `deliver_sm_resp` | `deliver_sm` |
| `generic_nack` |  |
| `query_sm` / `query_sm_resp` |  |
| `cancel_sm` / `cancel_sm_resp` |  |
| `replace_sm` / `replace_sm_resp` |  |


## Throughput and throttling

Throughput is the maximum number of [MT messages](https://community.sinch.com/t5/Glossary/MT-Mobile-Terminated/ta-p/7634) per second that can be sent via the SMPP account on the Sinch server.

- The default value is 10 per [bind](https://community.sinch.com/t5/Glossary/Bind/ta-p/7471).
- To increase this value, contact your [account manager](https://dashboard.sinch.com/dashboard).


The recommended default window size (maximum open requests) is 10.

The operator receiving the MT messages may have capacity limits. If so, it will restrict the overall throughput to a destination operator. For this reason, if any sorting of destination numbers is done, it is recommended to sort by last digit(s) as this will ensure a better distribution across various destination networks then when sorting by first digit.

## Enquire link

It's recommended to set `enquire_link` requests to 30 seconds.

## Time zone

Sinch SMSC uses UTC (Coordinated Universal Time)

## MSISDN Format

In GSM, MSISDN is built up as:

| MSISDN | CC + NDC + SN |
|  --- | --- |
| CC | Country Code |
| NDC | National Destination Code |
| SN | Subscriber Number |


For further information on the MSISDN format, see the [ITU-T specification E.164](https://www.itu.int/itu-t/recommendations/rec.aspx?rec=10688&lang=en).

## Next step

Review the [sending messages SMPP documentation](/docs/sms/smpp/send-message).

## Additional resources

- Review the [receiving messages SMPP documentation](/docs/sms/smpp/receive-message).
- [Get started with the REST SMS API](/docs/sms/getting-started).