# Create an SMPP SMSC trunk

Create an SMPP SMSC trunk so that DIDWW can connect and bind to your SMSC as
an ESME. Set the trunk name and **Server location**, enter the connection
details and credentials of your SMSC, limit the DID numbers that can be used as
the sender ID, and optionally add the trunk to an SMS trunk group.

For how DIDWW connects to your SMSC, see [SMPP SMSC trunk](../smpp-smsc-trunk.html).

## Before you begin

- An active DIDWW account is required. [Sign in to DIDWW](https://my.didww.com/users/sign_in) or [Create DIDWW account](https://my.didww.com/users/sign_up#/users/sign_up).
- Your SMSC must run an SMPP service that accepts bind requests from external
  ESMEs. See [Accept SMPP SMSC bind requests](accept-smpp-smsc-bind-requests.html).
- To use your DID numbers as sender IDs, at least one DID number with outbound
  P2P SMS enabled is required. See [P2P Outbound SMS
access](../../../how-sms-service-works.html#how-sms-service-works-p2p-access).

## Step 1: Open the creation form

1. In the DIDWW User Panel, go to **SMS > SMS Trunks**.
2. Click **Create New** in the top-right corner.
3. Select **SMPP SMSC**.

[![Create New menu on the SMS Trunks page with SMPP SMSC highlighted](../../../../_images/fig166.png)](../../../../_images/fig166.png)


**Fig. 1.** Select SMPP SMSC

## Step 2: Configure the General settings

In the **General** section, name the trunk, choose the DIDWW SMPP server that
binds to your SMSC, and enter the connection details and credentials of your
SMSC.

1. In **Friendly name**, enter a unique, descriptive name to identify the
   trunk.
2. Optionally, in **System type**, enter the value that your SMSC expects,
   for example `VMS` (voice mail system) or `OTA` (over-the-air activation
   system). DIDWW sends this value as the `system_type` bind parameter.
3. In **Server location**, select **US, NY** or **NL, AMS**. This is the DIDWW
   SMPP server that connects and binds to your SMSC.
4. In **Password** and **System ID**, enter the credentials that your SMSC
   requires to authenticate DIDWW during the bind.
5. In **Host**, enter the public hostname or IP address of your SMSC.
6. To connect to your SMSC over TLS, turn on **Use SSL**. **Use SSL** does not
   change the ports. Your SMSC must accept TLS connections on the ports you
   enter.
7. Optionally, in **Connection timeout**, change the time between TCP
   connection retries, in seconds.
8. In **TX port**, enter the port of your SMSC for the transmitter session, or
   for the single transceiver session when **Transceiver mode** is on.
9. In **RX port**, enter the port of your SMSC for the receiver session. DIDWW
   uses it only when **Transceiver mode** is off.
10. Turn on **Transceiver mode** if your SMSC supports a single transceiver
    session. Leave it off if your SMSC uses separate transmitter and receiver
    sessions.

Field definitions, defaults, and constraints are listed in [General
settings](../smpp-smsc-trunk-settings-reference.html#smpp-smsc-settings-general).

Important

DIDWW connects to your SMSC from the DIDWW SMPP server of the trunk's
**Server location**. Your firewall must accept connections from that
server's IP address. See [Server locations and IP
addresses](../../technical-data/smpp-specification.html#smpp-endpoints).

[![Create SMPP SMSC Trunk form with Server location and the SMSC connection fields in the General section](../../../../_images/fig23.webp)](../../../../_images/fig23.webp)


**Fig. 2.** Configure the General settings

## Step 3: Configure the source addresses

By default, **Allow any DID(s) for SMS OUT** is on, and all DIDs with Outbound
P2P SMS enabled in your account can be used as the sender ID. To allow only
specific DID numbers, restrict the source addresses. Otherwise, skip this
step.

1. In **Source Address Settings**, turn off **Allow any DID(s) for SMS OUT**.
2. In **Available source addresses**, select the DID numbers to allow. To find
   numbers, filter the list by **Source address**, **Description**,
   **Country**, or **Region**.
3. Click the right arrow button to add the selected numbers to **Allowed
   source addresses**, or click **Add all** to add every listed number. Only
   the numbers you add are available as sender IDs.

To remove numbers, select them in **Allowed source addresses** and click the
left arrow button, or click **Remove all**.

Field definitions are listed in [Source address
settings](../smpp-smsc-trunk-settings-reference.html#smpp-smsc-settings-source-address).

Note

When the **Allow any DID(s) for SMS OUT** toggle is turned off, the
**Available source addresses** list shows only DIDs that support outbound
P2P SMS.

[![Allow any DID(s) for SMS OUT turned off and a DID number moved from Available source addresses to Allowed source addresses](../../../../_images/gif110.gif)](../../../../_images/gif110.gif)


**Fig. 3.** Select the allowed source addresses

## Step 4: Add the trunk to a trunk group (optional)

You may assign the trunk to an existing SMS trunk group in order to enable
failover for inbound SMS. Within the trunk group, the trunk's priority
determines the order in which trunks will be used. If the trunk will not be
part of a trunk group, skip to Step 5.

1. Expand the **Trunk Group Configuration** section and select the group in
   **Assign to trunk group**.
2. In **Priority**, enter the trunk's priority within the group, from `0`
   to `32767`.

Field definitions are listed in [Trunk group
settings](../smpp-smsc-trunk-settings-reference.html#smpp-smsc-settings-trunk-group). To create a group, see [Create an
SMS
trunk group](../../trunk-groups/how-to-guides/create-sms-trunk-group.html).

Note

The system attempts to contact the target SMS trunk with the
highest-numbered priority first.

[![Trunk Group Configuration section of the Create SMPP SMSC Trunk form with the Assign to trunk group and Priority fields](../../../../_images/trunk_group2.webp)](../../../../_images/trunk_group2.webp)


**Fig. 4.** Configure the trunk group settings

## Step 5: Create the trunk

Click **Create** at the bottom of the page to save the new trunk.

The new trunk appears on the **SMS Trunks** page. DIDWW then starts the bind
process and connects to your SMSC from the DIDWW SMPP server of the selected
**Server location**, with the connection details and credentials you entered.
Creating the trunk does not assign it to a DID number.

[![Create button highlighted on the Create SMPP SMSC Trunk form](../../../../_images/create3.webp)](../../../../_images/create3.webp)


**Fig. 5.** Create the trunk

## Next steps

- Make sure that your SMSC accepts the bind requests that DIDWW sends. See
  [Accept SMPP SMSC bind requests](accept-smpp-smsc-bind-requests.html).
- [Check the connection status](check-smpp-smsc-trunk-connection-status.html)
  to confirm that DIDWW is bound to your SMSC.
- To receive SMS, [assign the trunk](../../../../phone-numbers/my-numbers/how-to-guides/assign-sms-trunk.html#assigning-sms-trunk) to one or more
  DIDs that support inbound SMS. For outbound SMS, DID assignment is not
  required.
- To send A2P messages with a verified Sender ID, associate an active
  [Sender ID Verification](../../../sender-id-verifications/index.html) with the
  trunk.

## Related resources

- [SMPP SMSC trunk settings reference](../smpp-smsc-trunk-settings-reference.html) - Look up field definitions,
  defaults, and constraints.
- [SMPP SMSC trunk](../smpp-smsc-trunk.html) - Understand how DIDWW connects
  and binds to your SMSC.
- [Assign an SMS trunk](../../../../phone-numbers/my-numbers/how-to-guides/assign-sms-trunk.html#assigning-sms-trunk) - Assign the trunk to one or
  more DID numbers to start receiving messages.
- [SMPP specification](../../technical-data/smpp-specification.html#service-incoming-sms) - Review protocol details,
  including encoding and concatenation.
- [Manage SMPP SMSC trunks](manage-smpp-smsc-trunk.html) - Edit or delete an
  existing SMPP SMSC trunk.
- [Sender ID Verifications](../../../sender-id-verifications/index.html) - Verify
  Sender IDs for A2P messaging through the trunk.