q.931

[Sivanesan Rathinam]

  Dear All - I have little confusion in callref W,r,t to Q.931 logs.

48551478: *Apr 15 12:35:01.112: ISDN Se0/1/1:15 Q931: RX <- SETUP pd = 8  callref = 0x00EF

    Sending Complete

    Bearer Capability i = 0x8090A3

        Standard = CCITT

        Transfer Capability = Speech 

        Transfer Mode = Circuit

        Transfer Rate = 64 kbit/s

    Channel ID i = 0xA18387

        Preferred, Channel 7

    Calling Party Number i = 0x0183, '12345678'

        Plan:ISDN, Type:Unknown

    Called Party Number i = 0xC1, '223344'

        Plan:ISDN, Type:Subscriber(local)

48551479: *Apr 15 12:35:01.112: ISDN Se0/1/1:15 Q931: Received SETUP  callref = 0x80EF callID = 0x007A switch = primary-net5 interface = User

48551480: *Apr 15 12:35:01.116: //-1/xxxxxxxxxxxx/SIP/Msg/sipDisplayBinaryData:

    Can you please clarify the difference between below callref , I know we need to follow up with callref = 0x00EF

RX <- SETUP pd = 8  callref = 0x00EF

callref = 0x80EF callID = 0x007A

SIVANESAN R       

[Nishant Savalia · Accepted solution]

Hi Siva,

The Call Reference value is used to associate messages with a particular channel connection.

It is possible to have two different calls using the same Call Reference value.

This is permissible by using the Call Reference Flag bit to associate which end of the link originated the call.

Below is the few value from right side of the call reference value

· 80 the router

· 81 the private network near the local user (possibly a local private branch exchange [PBX])

· 82 the public network near the local user (local telco switch)

· 83 the transit network (in the ISDN cloud)

· 84 the public network near the remote user (remote telco switch)

· 85 the private the network near the remote user (possibly a remote PBX)

· 87 the international network

· 8A a network beyond the internetworking point

In your example call ref = 0X80EF means your router has respond to the incoming call of the call ref = 0X00EF

Regards,

Nishant C.Savalia

[Sivanesan Rathinam]

Thanks for your response..

[Ayodeji Okanlawon · Accepted solution]

Usually on each isdn call, there are two call ref values. These are used to identify the direction of the call..1.e originating or terminiating side. The first bit is flipped depending o the direction of the call. The most significant bit is set on the call ref value..This bit determines if this messages is the originating or terminating side

In this example...

RX <- SETUP pd = 8  callref = 0x00EF---------------The most significant bit is 0---

callref = 0x80EF callID = 0x007A----------------------The most signifacant bit is 8..

NB That the last 3 bits are the same (0EF)

The originating side alwats uses 0 as its MSB and the terminating side uses 8...

When troubleshooting it is better to use the last 3 bits (0EF), as this will help you to see both the originating and terminating side of the call....

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"opportunity is a haughty goddess who waste no time with those who are unprepared"

[Sivanesan Rathinam]

Thanks for your response.

SIVANESAN R