How to configure transparent bridge between SCCP and SIP VoIP systems.

The First HAM of China said: Too simple, too young, sometime naive...

 

For too many reason, sometimes we have to manage 2 voip systems. One is running SCCP protocol, and the other one is running SIP protocol.

 

So, there's a problem: How to make the call route between two systems?

 

Cisco CME inculdes a mechanism, called "SIP Trunk" (CME 3.4 or later), it can register to a EXTERNAL sip proxy and make SCCP phones has ability to establish call with sip phones.

 

But the SIP Trunk has issues, your phone number will be translating to the number which registered to sip proxy. You can make the call to sip phones, but they cannot get your phone number.

 

For the incoming call from the SIP trunk, CME cannot identify the final destination number, it just translate the destination number to a specific number simply (in most cases the call will be transfer to the operator). Therefore,  they cannot call you back.

 

But, we found another way. CME support sip registrar, so just let the sip proxy register to CME with a trunk/provider line.

 

If your sip proxy donot support external call, you may adjust the sip parameter (INVITE, From, To, Remote-party-id, etc) both in CME and SIP Proxy. Otherwise the call may not establish.

 

The following part is configuration for CME.

 

 

 

voice service voip //enable sip proxy
 allow-connections sip to sip //allow sip call
 sip
  registrar server expires max 600 min 60
  no call service stop
!

voice class codec 1 //voice codec
 codec preference 1 g729r8
 codec preference 2 g711ulaw
 codec preference 3 g711alaw

!

voice register global //sip proxy global configuration
 mode cme
 source-address 172.16.0.17 port 5060 //router's ip add
 max-dn 48 //max numbers
 max-pool 24 //max phones
 authenticate realm CEM
 timezone 42
 time-format 24
 date-format YY-M-D
 create profile sync 0223779515054531
 ntp-server 192.43.244.18 mode directedbroadcast
!

!

voice register dn  1 //External sip proxy uses this number to rigister to CME

 number 3100

!

!
voice register pool  1
 id mac 0023.AEB6.78BE //MAC addr of the external sip proxy
 number 1 dn 1
 dtmf-relay rtp-nte sip-notify
 description SIP-PROXY-2000
 no vad
!

!
dial-peer voice 1 voip
 description **Outgoing Call to SIP Trunk**
 destination-pattern [1,2]...
 voice-class codec 1
 session protocol sipv2
 session target ipv4:172.16.0.25
 dtmf-relay rtp-nte
 no vad
!

!
dial-peer voice 2 voip
 description **Incoming Call from SIP Trunk**

 voice-class codec 1
 session protocol sipv2
 session target ipv4:172.16.0.25
 incoming called-number .%
 dtmf-relay rtp-nte
 no vad
!

sip-ua 
 calling-info pstn-to-sip from number set 3100
 registrar ipv4:172.16.0.25 expires 3600
 sip-server ipv4:172.16.0.25
 refer-ood enable