SIP Call Issue Troubleshooting Guide Content

1.  Understand the SIP Theory

Understand the NAT

Brief Introduction of SIP and SDP Protocol

How to Understand Inband Progress Option

Understand the PBX NAT Settings

How Do the PBX NAT Settings Work?


2. Perform the troubleshooting

Understand the different scenarios of SIP call

Understanding Voice Transmission of Remote Extension

Check List for SIP Call Issues

Common Causes for SIP Outbound Call Failures

How to Analyze the 30 Seconds Hangup Problem?


3. Refer the cases

- One-way audio & NAT related issue

Call Hangs up at 30 Seconds

The Router Settings Relevant with One Way Audio & 30 Seconds Call Hang up Issue

One-way Audio after Hold Retrieve from Cisco CUCM Extension

One-way Voice Issue when TA1610 Integrated with Cisco Cloud PBX


 - Internal Call Failure

Unable to Make Calls by TA FXS Ports - Invalid Caller ID Number Configured

Internal Call Failure - SRTP is not Enabled on the Phone


- Inbound Call Failure

Incoming Call Failure - Caused by Default SIP Port 5060 on PBX Changed

Calls are Rejected by Cisco SPA122 - Caused by Auth INVITE in Cisco SPA122

Incoming call from SIP trunk gets '401 Unauthorized' - Caused by Wrong SIP Port on SIP Trunk Settings

Unable to Receive Incoming Calls from the SIP trunk - Session Timer Required


- Outbound Call Failure

Intermittent Call Failure when Using TkReg SIP Trunk

Failed to Make Outbound Call - INVITE Packet Size Larger than Router MTU Requirement

Failed to Make Calls from TE/TB to SIP trunk When Caller ID is Blank

Outgoing Call via Peer Trunk Failed - Wrong DOD number

Unable to Make Outbound or Inbound Calls through SIP Trunk - ACL Strategy on Provider Side

SIP Trunk Status Unreachable - SIP Provider Didn't Respond the OPTIONS Packet from PBX

Outbound Call Failure when TA2410 Integrated with Mitel PBX

Failed to Make Outbound Calls - Line is Inactive


- Transfer Call Failure

Call Transfer failed- Caused by the T.38 Option


- Call Drop or Call Hangup issue during active call

Call Dropping after 5 min via SIP trunk - Carrier Response 420 Bad Extension

Call Dropped after One Hour -Timeout Limit on Provider Side

Calls Drop after 12 Seconds - Abnormal SIP Contact from the other SIP Device

Calls Drop after One Minute - Caused by Extension Max Call Duration(s)


4. Log Capture

If issue persists after you perform the above steps. try to get and post us the logs when you replicate the issue for further analysis.

1) System Log with Debug option enabled.

Here is the guide about how to get the System Log:

Also tick Debug option,

2) PCAP log

Here is the guide about how to get the PCAP capture:


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