2. tldr
  3. audiocodes
  4. direct-routing-for-enterprises

Configuring an AudioCodes SBC for Direct Routing (Enterprise)

This document assumes the following:

  • A Single IP Interface has been configured with the following:
    • Interface name: eth0
    • Application Type OAMP + Media + Control
    • NAT has been used
  • Mediant SW version 7.20A.254.376 or greater

Configure the Certificates

goto Setup > IP Network > Security > TLS Contexts

  • validate Security TLS Context 0
  • Request/issue a Public Certificate
  • Add Baltimore Root Certificate
  • Add Public CA Root & Intermediate Certificates
Parameter Value Comments
TLS Version TLSv1.2 Dependant on Public CA
DH Key Size 2048 (Minimum Recommended)

Recommeded CSR Settings

goto Setup > IP Network > Security > TLS Contexts > Change Certificate

Parameter Value
Subject Name[CN] sbc.directrouting.guide
Signatature Algorithm SHA1
Private Key Size 2048 Minimum recommended

Install the Certificate

goto Setup > IP Network > Security > TLS Contexts > Direct Connect > Change Certificate

  • Upload Certificates
  • Load Private Key (if Applicable)
  • Load Device Certificate (PEM Format)

Install Root and Intermediate Certifiates

goto Setup > IP Network > Security > TLS Contexts > Select DirectRouting > Trusted Root Certificates

  • Select and Import the certificates
  • Install Baltimore Certificates
  • Install Issuing and Root CA
Certificate link comments
Baltimore Certificates Baltimore Certificates  
Root CA letsencrypt.org IMPORTANT This will be based on certificate purchased for the SBC, in lab environments I use free 90 day certs from letsencrypt.org and if I need longer than that I generally use digicert.com
Intermediant CA letsencrypt.org (Cross-Signed byIdenTrust) letsencrypt.org (Signed by ISRG Root X1) IMPORTANT This will be based on certificate purchased for your SBC, in lab environments I use free 90 day certs from letsencrypt.org and if I need longer than that I generally use digicert.com

Configure NTP Settings

goto Setup > Administration > Time & Date

  • Enable NTP
  • Configure Primary NTP Server
  • Configure UTC Offset
  • Configure Daylight Savings
Parameter Required Values Comments
Enable NTP Enable  
Primary NTP pool.ntp.org As per customer Requirements
UTC Offset 3600 As per customer Requirements
Daylight Savings Enabled As per customer Requirements

Configure Syslog Settings

TroubleShoot > Logging > Syslog Settings

  • Enable Syslog
  • Configure Syslog Server IP

Syslog software can be downloaded from AudioCodes

Configure the Syslog Settings

Parameter Value Comments
Enable Syslog Enable  
Syslog Server 10.0.0.5 As per customer requirement’s
Debug Level Detailed  

Configure Default DNS Settings (Optional)

goto Setup > IP Network > DNS > DNS Settings

  • Configure Primary DNS Server
  • Configure Secondary DNS Server
Parameter Value Comments
Primary DNS 1.1.1.1 As per customer Requirements
Secondary DNS 1.0.0.1 As per customer Requirements

Configure the Media Realm

goto Setup > Signaling and Media > Core Entities > Media Realms

SIPTrunk Media Realm

Parameter Value  
Index 0  
Name SIPTrunk  
Topology Location Up  
IPv4 Interface Name #0 [eth0] As per customer Requirements
Port Range Start 6000 As per customer Requirements
Number of media session legs 10 As per customer Requirements
Default Media Realm No  

Direct Routing Media Realm

Parameter Value  
Index 1  
Name DirectRouting  
Topology Location Down  
IPv4 Interface Name #0 [eth0]  
Port Range Start 7000 As per customer Requirements
Number of media session legs 10 As per customer Requirements
Default Media Realm No  

Configure the SIP Interfaces

goto Setup > Signaling and Media > Core Entities > SIP Interfaces

SIPTrunk SIP Interface

Parameter Value Comments
Name SIPTrunk  
Network Interface #0 [eth0] as per sbc configuration
Topology Location UP  
UDP port 5061 as per SIPTrunk Requirements
TCP Port 0  
TLS Port 0  
Enable TCP Keepalive Enable  
Media Realm #0 [SIPTrunk] as per sbc configuration
TLS Context Name -  
Classification Failure Response Type 500 Default

Direct Routing SIP Interface

Parameter Value Comments
Name DirectRouting  
Network Interface #0 [eth0] as per sbc configuration
Topology Location Down  
UDP port 0  
TCP Port 0  
TLS Port 5067 user defined
Enable TCP Keepalive Enable  
Media Realm #1 [DirectRouting] as per sbc configuration
TLS Context Name #1 [DirectRouting] as per sbc configuration
TLS Mutual Authentication Enable  
Classification Failure Response Type 0 Recommended to prevent DoS attacks

Configure Proxy Sets & Proxy Address

goto Setup > Signaling and Media > Core Entities > Proxy Sets

  • Configure proxy set SIPTrunk
  • Configure proxy address SIPTrunk
  • Configure proxy set direct routing
  • Configure proxy address direct routing

SIPTrunk Proxy Set

Parameter Value Value
Index 0
Name SIPTrunk
SBC IPv4 SIP Interface #0 [SIPTrunk]
Proxy Keep Alive Using OPTIONS

SIPTrunk Proxy Address

**Setup > Signaling and Media > Core Entities > Proxy Sets > Add Proxy Address **

Parameter Value
Proxy Address [siptrunk]:[signalling port]
Transport Type UDP

Configure Proxy Sets

Setup > Signaling and Media > Core Entities > Proxy Sets

Parameter Value Value
Index 1
Name DirectRouting
SBC IPv4 SIP Interface #1 [DirectRouting]
TLS Context Name #1 [DirectRouting]
Proxy Keep Alive Using OPTIONS
Proxy Hot Swap Enable
Proxy Load Balancing Method Random Weights

Configure Proxy Address - Direct Routing

Setup > Signaling and Media > Core Entities > Proxy Sets > Add Proxy Address

Parameter Value
Proxy Address sip.pstnhub.microsoft.com:5061
Transport Type TLS
Proxy Priorty 1
Proxy Random Weight 1
Parameter Value
Proxy Address sip2.pstnhub.microsoft.com:5061
Transport Type TLS
Proxy Priorty 2
Proxy Random Weight 1
Parameter Value
Proxy Address si3p.pstnhub.microsoft.com:5061
Transport Type TLS
Proxy Priorty 3
Proxy Random Weight 1

Configure Coder Group

Setup > Signaling and Media > Coders and Profiles > Coder Groups

  • Update Coder Group 0

Recommend you update the coder specifically for SIP TRUNK providor !

Coder Name Packetization Time Rate Payload Type Silense Suppression Coder Specific
G.711A-law 20 64 8 Disabled  
G.711U-law 20 64 0 Disabled  
  • Create a new Coder Group 1

Recommend you create a new coder specifically for Direct Routing !

Coder Name Packetization Time Rate Payload Type Silense Suppression Coder Specific
SILK-NB 20 8 103 N/A  
SILK-WB 20 16 104 N/A  
G.711A-law 20 64 8 Disabled  
G.711U-law 20 64 0 Disabled  
G.729 20 8 18 Disabled  

Configure IP Profiles

Setup > Signaling and Media > Coders and Profiles > IP Profiles

  • Configure SIPTrunk IP Profile
  • Configure Direct Routing IP Profile

Configure SIPTrunk IP Profile

Parameter Value comments
Name SIPTrunk  
SBC Media Security Mode RTP As per your SIP Trunk
Extension Coders Group #1 [Audio_Coders_Groups_1]  
P-Asserted-Identity Header Mode Add Required for Anonymous calls
Remote REFER Mode Handle Locally  
Remote Replaces Mode Handle Locally  
Remote 3xx Mode Handle Locally  
Remote Multiple 18x Not Supported ONLY Required if you get Ringback then silence

Configure Direct Routing IP Profile

Parameter Value comments
Name DirectRouting  
SBC Media Security Mode SRTP  
Remote Early Media RTP Detection Mode By Media  
Extension Coders Group #1 [Audio_Coders_Groups_1]  
RTCP Mode Generate Always  
ICE Mode Disabled/Lite Only Enable Lite if you enable Media Bypass, otherwise keep disabled
SIP Update Support Not Supported  
Remote Re-Invite Support Supported only with SDP  
Remote Delayed Offer Support Not supported  
Remote REFER Mode Handle locally  
Remote 3xx Mode Handle locally  
Remote Hold Format Inactive  

Configure IP Group

goto Setup > Signaling and Media > Core Entities >_ IP Group_

  • Configure SIPTrunk IP Profile
  • Configure Direct Routing IP Profile

Configure SIPTrunk IP Group

Parameter Value
Name SIPTrunk
Topology Location Up
Proxy Set #1 [SIPTrunk]
IP Profile #1 [SIPTrunk]
Media Realm #0 [SIPTrunk]

Configured DirectRouting Group

Parameter Value
Name DirectRouting
Topology Location Down
Proxy Set #2 [DirectRouting]
IP Profile #2 [DirectRouting]
Media Realm #1 [DirectRouting]
Classify By Proxy Set Disable
Local Host Name sbc.directrouting.guide
Always Use Src Address Yes
Proxy Keep-Alive using IP Group settings Enabled
DTLS Context #1 [DirectRouting]

Configure SRTP

goto Setup > Signaling and Media > Media > Media Security

Parameter Value
Media Security Enable
Media Security Behavior Preferable

Configure Message Condition Rule

Setup > Signaling and Media > Message Manipulation > Message Condition

Parameter Value
Index 0
Name DirectRouting-Contact
Condition header.contact.url.host contains ‘pstnhub.microsoft.com’

Configure Classification

Setup > Signaling and Media > SBC > Classification Table

Parameter Value
Index 0
Name DirectRouting
Source SIP Interface DirectRouting
Source IP Address 52.112..
Destination Host sbc.directrouting.guide
Message Condition DirectRouting-Contact
Action Type Allow
Source IP Group #2 [DirectRouting]
Parameter Value
Index 1
Name DirectRouting
Source SIP Interface DirectRouting
Source IP Address 52.113..
Destination Host sbc.directrouting.guide
Message Condition DirectRouting-Contact
Action Type Allow
Source IP Group #2 [DirectRouting]
Parameter Value
Index 2
Name DirectRouting
Source SIP Interface DirectRouting
Source IP Address 52.114..
Destination Host sbc.directrouting.guide
Message Condition DirectRouting-Contact
Action Type Allow
Source IP Group #2 [DirectRouting]
Parameter Value
Index 3
Name DirectRouting
Source SIP Interface DirectRouting
Source IP Address 52.115..
Destination Host sbc.directrouting.guide
Message Condition DirectRouting-Contact
Action Type Allow
Source IP Group #2 [DirectRouting]

Configure IP to IP Routing

Setup > Signalling and Media > SBC > Routing > IP-to-IP Routing

  • create options terminate
  • create refer terminate
  • create SIPTrunk to Direct Routing
  • create Direct Routing to SIPTrunk

Option Terminate

Parameter Value
Index 0
Name OPTIONS Terminate
Source IP Group Any
Request Type Options
Destination Type Dest Address
Destination Address Internal

Refer Terminate

Parameter Value
Index 1
Name REFER
Source IP Group Any
Call Trigger Refer
ReRoute IP Group #2 [DirectRouting]
Destination Type Request URI
Destination IP Group #2 [DirectRouting]

Sip Trunk to Direct Routing

Parameter Value
Index 2
Name SIPTrunk to DirectRouting
Source IP Group #1 [SIPTrunk]
Destination Type IP Group
Destination IP Group #2 [DirectRouting]

Direct Routing to Sip Trunk

Parameter Value
Name DirectRouting
Source IP Group #2 [DirectRouting]
Destination Type IP Group
Destination IP Group #1 [SIPTrunk]
Index SourceIP subnet Start Port end Port Protocol Use Specific Interface Interface ID Allow Type
0 52.112.0.0 14 0 65535 Any Enabled #0 [eth0] Allow
1 SIPTrunk subnet 0 65535 Any Enabled #0 [eth0] Allow
49 0.0.0.0 0 0 65535 Any Enable #0 [eth0] Block