SMS and MMS for BYO PBX
Connect your own messaging provider to a SessionCloud BYO PBX project so users can send and receive SMS and, where supported, MMS in the softphone. Your provider account supplies the messaging service, and you choose which softphone account uses each number.
Compare providers and connection options for the SMS/MMS support matrix, additional providers, custom SMS gateways and direct customer-hosted messaging services.
Availability. Use an app version and portal that support your selected messaging provider. If provider controls are missing, contact SessionTalk to enable this feature for your portal.
This setup applies to BYO PBX plans. Teams Hosted plans use their own messaging setup.
If you operate the app’s inbox and messaging API, see Direct customer-hosted messaging. That integration provisions the app to contact your service directly and has separate portal/app release requirements. Custom SMS gateway sends through SessionCloud to your outbound gateway.
Use Custom SMS gateway when you have an existing SMS gateway, including a bridge for a provider without a built-in integration, and want SessionCloud to manage the inbox, message history and notifications. Your gateway must support the configured request format or translate it to the provider’s API. Use Customer-hosted messaging service when your server runs the full app-facing messaging service. See gateway setup for the requirements and examples.
Before you start
You need access to the SessionCloud project, a supported provider account, and a number enabled for SMS. You also need the SIP username and domain of the softphone account that will use the number.
Your messaging number can be separate from your calling number. Enabling the SMS option in SessionCloud makes messaging available in the app; it does not activate SMS on a provider’s phone number.
Choose your provider
| Provider | Details to have ready | Setup guide |
|---|---|---|
| Telnyx | API key, public key, messaging profile and SMS number | Set up Telnyx |
| Twilio | Account SID, Auth Token and SMS number | Set up Twilio |
| DIDWW | HTTP OUT trunk username and password, SMS-enabled number, and HTTP IN trunk | Set up DIDWW |
| VoIP Innovations / Sangoma | Wholesale API username and password, messaging number and authorized SessionCloud server IPs | Set up Sangoma |
| Andrews & Arnold | Messaging number and dedicated outgoing SMS password | Set up A&A |
| Custom SMS gateway | Gateway URL, credentials and incoming/outgoing field mappings | Set up a gateway |
| Customer-hosted messaging service | App-facing service URLs and each user’s service credentials | Connect directly |
Additional providers available in the portal
Select these connections from the portal provider menu. SMS, MMS and delivery-status support differ by integration; follow the matching setup guide.
| Provider | Messaging supported | Setup guide |
|---|---|---|
| SignalWire | SMS | Set up SignalWire |
| Flowroute | SMS and MMS | Set up Flowroute |
| Bandwidth | SMS | Set up Bandwidth |
| Voxtelesys | SMS and MMS | Set up Voxtelesys |
| Telgorithm | SMS and MMS, up to five attachments | Set up Telgorithm |
| Tychron | SMS | Set up Tychron |
| IntelePeer | SMS | Set up IntelePeer |
| VoIP.ms | SMS and MMS, up to three attachments | Set up VoIP.ms |
| Esendex USA | SMS | Set up Esendex USA |
| Inteliquent | SMS and MMS | Set up Inteliquent |
| Clearfly | SMS and MMS, one attachment | Set up Clearfly |
See all messaging providers for credentials, callback requirements, attachment sizes and delivery-status limitations.
Set up messaging
The project owner can enter credentials, assign numbers and copy the generated webhook URL directly in the portal. You do not need to send API passwords to SessionTalk support. Follow the separate direct-service guide for customer-hosted connections, which do not generate a SessionCloud webhook.
- Open the BYO PBX project in SessionCloud and go to Provisioning > Advanced > Messaging.
- Enable SMS.
- Under Incoming and outgoing SMS, choose a Messaging provider to open its settings and follow the relevant setup guide above. Saved connections appear as compact rows; select Configure to edit one.
- Select Save at the bottom of the page. This saves the project settings and every provider connection you have edited.
- Use Copy URL beside the provider’s Webhook URL, then paste it into your provider’s incoming-message settings.
- Manually assign a messaging number to each SIP account that needs SMS or MMS. Accounts used only for calls do not need an assignment.
- Connect the app, then test sending, receiving and background notifications.
A project can connect several messaging providers. Each assigned number uses one provider connection. You can switch between providers while editing; the bottom Save button saves all edited connections. If a provider fails to save, its entered details remain available for correction and retry.
Enter phone numbers in full international format, starting with + and the country code, for example +447700900123. Use the SIP account details when assigning a number, rather than the user’s display name.
Configure the provider connection once, then repeat the assignment for each messaging user. Each SIP account can have one messaging number, and a number can belong to one SIP account. To change an assignment, disable it first. Reassignment starts a new message history and requires updated account provisioning.
Connect the app
The app uses the messaging API with configuration specific to its assigned number. Saving a provider connection, entering the carrier webhook URL and assigning a number do not by themselves deliver that configuration to the app.
After saving the assignment, supply updated account configuration through your authenticated external-provisioning service or generate a private account provisioning QR code in the portal. Use the same SIP username and domain as the assignment, and an app version that supports the selected messaging provider. The portal includes the matching messaging configuration with that account’s provisioning.
For users who entered their SIP credentials manually, entering those credentials or a Provider ID alone does not supply Sangoma or other general BYO messaging configuration. Provide account provisioning before testing messaging. Direct Telnyx SIP accounts on sip.telnyx.com have a separate automatic enrollment flow in supported apps.
Open the app with the configured account enabled and test sending and receiving. In the portal, select Messaging activity > Refresh status:
- Enabled means the number assignment is active.
- Last received SMS shows when SessionCloud last stored an incoming message. It does not confirm that the message reached the phone.
SessionCloud routes messages through the messaging API; SIP registration remains with the customer’s PBX. Confirm message delivery and notifications in the app. SessionCloud accounts receive their messaging API configuration through account provisioning.
Receiving messages
Messages sent to the assigned number appear in Messages in the softphone. Mobile users can receive a notification while using another app or while the phone is locked. Notifications require internet access, push enabled for the account and permission to show notifications on the phone.
If the phone is offline or an alert is missed, opening the app after reconnecting lets it check for new messages. Notification previews depend on the phone’s privacy settings.
What to test
Ask the user to send a short text to a test mobile number and reply to it. Then leave the softphone using the phone’s Home gesture, lock the screen and send another reply. Confirm that the notification opens the correct conversation. Repeat on Wi-Fi and mobile data.
These guides cover one-to-one messaging. MMS is available for enabled Telnyx and Sangoma numbers, and through the Flowroute, Voxtelesys, Telgorithm, VoIP.ms, Inteliquent and Clearfly connections. Check the provider comparison for attachment limits and carrier requirements. Direct customer-hosted messaging services can implement the MMS extension. Twilio text support does not establish MMS support in this integration. Multi-recipient group MMS is not supported.
For everyday use, see Provider text messages. For setup problems, see Troubleshooting SMS.