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ISDN E1 R2 Blocking "Call Collect" calls.

Hi Guys,

Hope you can help. We have recently migrated a site in Brazil from a MD110 to CUCM

The end users would like to block Call collect callscoming in from the PSTN to all extensions except 4 special phones.

I have not used E1R2 before and the lines came up first time from Cisco example for Brazil so haven't had much dealings with in since.

Currenly a external person can place a call from their mobile with a prefix followed by our normal telephone number. The call is then placed to our phones and the CLI only show the user mobile number. When they answer they hear a message saying someone want to make a call collect call. Hang up or stay on the line to accept.

Below are the relevant parts of the 3825's config. Any help /config will be appriciated.

SAO1#show ver

Cisco IOS Software, 3800 Software (C3825-SPSERVICESK9-M), Version 12.4(20)T1, RELEASE SOFTWARE (fc3)



controller E1 0/0/0

framing NO-CRC4

clock source line primary

line-termination 75-ohm

ds0-group 0 timeslots 1-15,17-31 type r2-digital r2-compelled ani

cas-custom 0

country brazil use-defaults


category 2

answer-signal group-b 1

description link to TELCO


voice-port 0/0/0:0

cptone BR


Let me know if you need any further info.

Thanks in advance.



Hall of Fame Super Gold

Re: ISDN E1 R2 Blocking "Call Collect" calls.

Unfortunately is not possible to do so.

When a collect call comes in R2, it only possible to block (answer signal B7) or accept it unconditionally:

That is, ASAIK there is no configuration mechanism that would let you selectively accept collect calls for certain extensions only.

The workaround would be an arrangement with telco to have them send calls for the desired extension on a subset of channels only, you would then configure two cas-groups with different options. However, you will find that usually either customer or telco do not want to do this.

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