Overview

All of the outbound calls through Edgemarc started to fail.

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Prerequisites

• Screenconnect access
• Hepic access
• Edgeview access

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Solution

To start with troubleshooting, we will need call samples. Open a ticket with Support, making sure to describe the issue and any symptoms you observe, and add at least two call samples in the following format:

• Calling From Number:
• Calling To Number:
• Date of call: dd/mm/yy
• Time of call: xx:xx am/pm (time zone)
• Result: ex: dropped call, garbled audio, etc.
• Trouble observed: Inbound / Outbound / Both directions

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As only the outbound calls are failing, it means that Edgemarc itself is up and running, so the first step is to review the reported calls in Hepic:

1. From one of the Screenconnect VMs in the corresponding Data Center, look up the customer samples in Hepic.
2. Filter by the caller or called number and make sure the timestamp matches with the reported calls.
3. Proceed based on your findings and Known Cases.

Known Cases

Edgemarc firmware issues

In one known case, the SIP traces for the calls reported had 503 Service Unavailable response code:

From the signaling analysis, the reason for this 503 message was that an SDP block was being stripped from the 183 messages when passing through the Edgemarc:

• This is how it looks at the inbound leg:

SIP/2.0 183 Session Progress
Via: SIP/2.0/TLS 190.120.11.134:5061;branch=z9hG4bK141039423
From: "60034052" <sip:60034052@c1s.sbc.cul.sbcaas.com>;tag=f5GGZ6IPdcPhFTnyu49FB360F7579137
To: <sip:+50325115500@31.25.112.28>;tag=gK009489d3
Call-ID: 777603622@190.120.11.134
CSeq: 801 INVITE
Contact: <sip:+50325115500@31.25.112.28:5061;transport=tls>
Allow: INVITE,ACK,CANCEL,BYE,REFER,NOTIFY,PRACK,UPDATE,OPTIONS
Require: 100rel
RSeq: 474332
Content-Length: 334
Content-Disposition: session; handling=required
Content-Type: application/sdp
v=0
o=Sonus_UAC 727372 751167 IN IP4 31.25.112.28
s=SIP Media Capabilities
c=IN IP4 31.25.112.23
t=0 0
m=audio 46494 RTP/SAVP 8 101
a=crypto:2 AES_CM_128_HMAC_SHA1_80 inline:yXttN7mFNyqEhDJVxSHyjcs1SzG2De6JTmEZpDUz
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=sendrecv
a=ptime:20
a=rtcp:46495

• The modified 183 message looked like this:

SIP/2.0 183 Session Progress
Via: SIP/2.0/TLS 190.120.11.134:5061;branch=z9hG4bK141039423
From: "60034052" <sip:60034052@c1s.sbc.cul.sbcaas.com>;tag=f5GGZ6IPdcPhFTnyu49FB360F7579137
To: <sip:+50325115500@31.25.112.28>;tag=gK009489d3
Call-ID: 777603622@190.120.11.134
CSeq: 801 INVITE
Contact: <sip:+50325115500@31.25.112.28:5061;transport=tls>
Allow: INVITE,ACK,CANCEL,BYE,REFER,NOTIFY,PRACK,UPDATE,OPTIONS
Require: 100rel
RSeq: 474332
Content-Length: 334
Content-Disposition: session; handling=required
Content-Type: application/sdp

In this case, the Action Log for the Edgemarc indicated that the device had been recently upgraded, so the immediate workaround for this was to downgrade the EdgeMarc to its previous release:

If the issue persists, a case should be opened with Ribbon to investigate Edgemarc's behavior.

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Based on the troubleshooting, the Support team will either take action to fix the issue on our side or reach back with findings and any next steps required from you.

Verification

Once the root cause is fixed, try to replicate the issue to confirm that it is no longer there.