Need help with Calling and Called Numbers?

[techToddler]

Hello Friends,

I always tend to have a bit confusion with this calling and called number.

Am I correct with the below,

Calling number - From where the call was dialed or originated?

Called Number - to where the call going to or terminated?

Is there a proper way to understand this in leyman term?

Next in below example what would be the calling and called number,

IP Phone dialing 512-475-6524

IP Phone (2020 - Mask as 3035428796) ----> CUCM----->SIP trunk----->Gateway----->PSTN

1. What is the calling and called party between IP Phone and CUCM?

2. From CUCM and Gateway?

Do anywhere is it changing considering this without any digit manipulation done so far?

Regards

Sanjay.

[Chakshu Piplani]

Hi Sanjay,

The calling number will be 2020 and the called number will be 512-475-6524, through out the call, since there is a mask, that should show up in "P-Asserted-Identity:" of the SIP Invite from CUCM to GW.

The From and To Fields should have 2020 and 5124756524 respectivly.

I would suggest taking collecting "debug ccsip messages" on gateway and check this for your better understanding.

Regards,

Chakshu Piplani

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[Vivek Batra · Accepted solution]

Hi Sanjay,

I try to put in other way around. 

Calling number (ANI) - Who dials the number

Called number (DNIS) - Number being dialed

These numbers could be modified during different part of the call flow and may not remain fixed.

For example, your phone DN is 2020 and you want the call should route to 09925801882 even if you dial 1234. So;

1. 2020 dials 1234. Here calling number is 2020 and called number 1234 from phones perspective.

2. Call reaches to CUCM. CUCM applies digit manipulation techniques (either at TP, RL/RG etc) to convert DNIS to +919925801882. Say ANI remains unchanged. This call is sent to gateway t hen. Here calling number is still 2020 and called number is +919925801882 from CUCM perspective. As Chakshu said, you can verify the information in SIP INVITE.

3. Call comes to gateway. Gateway changes the ANI from 2020 to 30442020 and DNIS from +919925801882 to 9925801882. Here calling number is 30442020 and called number is 09925801882 from gateway perspective.

- Vivek

[techToddler]

Thank you Vivek for your brief explanation with example ( most cases I understand with that). I got it.

Thanks Chakshu as well.

Regards

Sanjay