ISDN GW 3241 ; admin config guide

[gavin han]

Hi, I'm new to ISDN Gateway. I was trying to find admin and config guide but no luck. Could you please provide link to admin, config guide and best practices to configure ISDn gateway?

Thanks in advance.

[Jens Didriksen]

Try these:

http://www.cisco.com/en/US/docs/telepresence/infrastructure/isdn_gw/install_guide/isdn_gw_3241_getting_started_mar2011.pdf

http://www.323.tv/products/multi-point-conferencing/gateways/codian-isdn-gw-3241/codian-isdn-gw-3241/userguide

/jens

[Martin Koch]

in addition to what Jens said, the official documentation link is:

http://www.cisco.com/en/US/products/ps11448/tsd_products_support_series_home.html

[Tomonori Taniguchi · Accepted solution]

Two important configuration on ISDN Gateway as additional information for your reference (addition to administrator guide).

1) Service Prefix configuration on ISDN Gateway

Make sure this service prefix number doesn’t overlap with any other Endpoint/MCU alias.

You may utilize VCS for SIP/H323 Interworking as well.

• ISDN Gateway register to VCS with “Dial plan prefix” (Note, each dial rules doesn’t register to VCS individually).

       

       

2) Dial plan configuration

The inbound dial plan and outbound dial plan are separate configuration.

Here is some sample dial plan configuration per call scenario.

Example 1: Using VCS to dial (IP to ISDN dial rules )

• Called number matches: 2511(D+)
• Call this number: $1
• Explanation: $1 refers to the first bracketed group in the number match field.
  This is D+, which means one or more of any digit.
  By putting the “2511” first we exclude it from the D+ group, which means we are left with a valid PSTN number to dial. So the user could dial 251101234567 from their phone and the ISDN Gateway would strip the 2511 and dial 01234567 over the PSTN.

   

Example 2: Auto Attendant (IP to ISDN dial rules )

• Called number matches: 2510
• Action: “Enter the auto attendant”

    DTMF keys

• Digits 0 to 9
• # (hash), to indicate that you have completed the number and to start dialing

    FECC control

• If FECC is enabled on your endpoint, use the Left arrow to delete the last character and the Right to start dialing.

   

Example 3: Using VCS to dial (ISDN to IP dial rules)

• Called number matches: 623065(D+)
• Call this number: 906580$1
• Explanation: Last two digit of incoming ISDN call added to “906580” and forward to VCS for alias
  So the user dial-in 62306530 then GW strip “30” and add it into 906580 which come out 90658030 and process farther call negotiation with VCS

   

Example 4: Auto Attendant (ISDN to IP dial rules)

• Called number matches: 62303640
• Action: “Enter the auto attendant”

    FECC control

• If FECC is enabled on your endpoint, use the Left arrow to delete the last character and the Right to start dialing.

    DTMF keys

• Digits 0 to 9
• * (asterisk or star), which is interpreted as a dot (.) for ISDN to IP calls
• ** interpreted as a “:” and used as an extension separator for ISDN to IP calls
• # (hash), to indicate that you have completed the number and to start dialing

   

[Elliot Osbourne]

Hi,

I have been reading through this thread and have a question regarding ISDN GW security.

I have always been under the impression that configuring an ISDN GW with rules to enter the auto attendant poses a security threat with regards to "hairpinning" or "Dial Through Fraud".

Have I misunderstood and is it now safe to have this rule as I always configure the lead ISDN number to dial the auto attendant of an MCU if available or an endpoint directly?   

Thanks

Elliot

[Martin Koch]

It is as secure as you configure it. If you do not use any limitation, then sure, if somebody exploits your

number and prefix he will be able to dial out again.

But you can use your call control, like if you have the VCS, you could put the ISDN GW in

a specific subzone and add to the CPL that calls from and to this subzone are not allowed.

Not using the IVR and  / or the main number is a good idea as well or as you described to point it so

something else.

Also be reminded that the latest mcu versions can be configured to dial out as a conference participant

via the OSD, so be aware of that as well.

Also if you know that you never dial high price destinations it will make sense to block them in the call control and the isdn gw as well.

Its also worth asking your isdn network provider to block outbound number ranges, set a cost limit or ask him what

other recommendations he has to limit fraud or at least the impact of it.

Btw, most fraud attempts got aware of were ip2isdn, but yes, I had also seen ISDN2ISDN.

[Tomonori Taniguchi]

Other information which become handy for configuring the dial plan, the Syntax for conditions (Called number matches)

[gavin han]

Thanks all for kind help. could questions came up in my mind:

1. Since, ISDN gateway registers as h323 gw to VCS. would it be advisable to register enpoints to VCS as h323?

2. Should I register endpoints to VCS as h323 or sip with their ISDN number? i.e. if endpoint ISDN number is 5104348989 than should I register it to VCS with 5104348989?

3. How would our provider send ISDN calls to our ISDN gateway? i.e. if our end points are 5104348989, 3434348989, 8904348989 than how would our provider know that they need to divert call to our ISDN gateway if these 3 numbers are dialed?

Thanks...

[Jens Didriksen]

1. Yes

2. You can register your end-points with both SIP URIs and H.323 Aliases, and yes, you can use your ISDN number as E.164 Alias.

3. When using a ISDN GW you would normally have PRI connected to it - see

http://en.wikipedia.org/wiki/Primary_Rate_Interface

How many channels you require is something you need to work out with your provider, your provider should then also issue you with a number range you can use.

You should assign service prefixes to the GW, which it will register with the VCS-C, and the E.164 Alias should be prefixed with this when you want to make outbound ISDN calls.

I.e. let's say your E.164 Alias is 12345678, and you have assigned two service prefixes on the GW; #1 for ISDN video calls and #2 for phone calls - when wanting to do an ISDN video call, you now dial #112345678, and the VCS-C will route the call to the GW.

For incoming ISDN calls, people would just dial 12345678 as this is part of the number range issued by your ISDN provider, and this will hit your GW and will be routed by VCS-C to the end-point which is registered with the 12345678 E.164 Alias.

/jens

[gavin han]

Thank you so much. I very much appreciate your kind help . one more questions: I'll have to register ISDN gateway to VCS as H.323. what e.164 alias should I use? can I use any alias?

[Jens Didriksen]

I've got a couple of TANDBERG Gateways, and these only registers with the video and voice pre-fixes, not an E.164 Alias.

If your GW require an E.164 Alias then your IVR/Auto-Attendant number might be the appropriate one to use.

(Please reate the answers you find helpful)

/jens

[gavin han]

Thanks Jens. what voice and video prefix should be used to register it to VCS?

[Jens Didriksen]

The prefix to be used is entirely up to you, but it will tell the VCS-C to route any calls starting with those numbers and/or symbols to send the call to the Gateway. There is an example of this in the extensive and detailed post by Tomonori.

/jens

[gavin han]

Thanks you Jens and Tomonori. I appreciate your kind help.

for IP to ISDN calls for endpoints registered on VCS-C.

suppose I'm registering Endpoints to VCS-C and ISDN gateway registers to VCS-C with prefix 25. in order to send ISDN calls from Endpoints to ISDN, will I have to setup configure "Search rules" on VCS-C to route ISDN calls (prefixed with 25, i.e. 252124531212)? or I won't need "Search Rules" for this since ISDN gateway is registered with prefix "25" on VCS-C?

Thanks Again!

[Jens Didriksen]

That's right, no search rules needed for this as anything starting with 25 will go to the GW - that's also why it's important to choose the prefixes carefully so you don't accidently send calls to the GW.

A lot of people, including us, includes a # in the prefix  - i.e. 25# - and as it breaks the dial string, it also helps with preventing unauthorized access from external sources.

See https://supportforums.cisco.com/message/3542518 for more on this.

/jens