This article relates to the Cisco TelePresence ISDN GW 3241 and Cisco TelePresence ISDN GW MSE 8321 products.
Q. Please explain the Codian ISDN GW's use of the Send calling number option with Deutsche Telekom circuits
A. Some ISDN switches set restrictions on the number of digits in the E.164 number and this is configurable by the PRI provider. At some customer sites we have found that when this option is set and the number of digits being sent by the Codian ISDN GW is not the same as the number configured by the PRI provider, the call can be dropped or "0" is sent instead of the correct E.164 number.
Then, if your PRI has been configured by your provider, for example Deutsche Telekom, for a 2-number extension (0-99) and you try to dial with a 3-digit extension, or extension numbers not in the range allowed, the PRI may not allow you to place any outgoing calls.