To better assist you, could you please provide some additional information?
- Are you using a specific PBX or VoIP system (for example, Cisco Unified Communications Manager, Asterisk, Avaya, etc.)?
- Is the PSTN connectivity provided by a gateway, SIP trunk, or another type of connection?
- Are you getting any error messages or codes when you try to place a PSTN call?
- Has this issue been happening suddenly, or was it set up recently and never worked as expected?
- Have there been any recent configuration changes or network updates that might be related?
In the meantime, here are some general troubleshooting steps you can consider:
• Verify your trunk or gateway configuration. Check that the settings (such as SIP credentials, dial plan prefixes, or digital line configurations) are correct.
• Ensure that your dial plan is correctly configured. The dialed number should be routed to the PSTN properly.
• Check if there is any firewall or network rule that could be blocking the traffic for PSTN calls.
• Review system logs or call detail records (CDRs) to see if there are any clues regarding the failure.
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