Country specific telephony conventions

Although ISDN (BA/PRA) technology is standardized, the convention of number formatting/composition is not. Some countries use a slightly different technique to deliver the number to the ISDN interface. Below, you'll find an overview of the known quirks which are the convention in a certain country.

Belgium

Conforms to the European ISDN convention.

When dealing with a BA line, please ask the operator to configure it:

• Point-to-point
• Layer 2 persistent up

France

Conforms to the European ISDN convention.

Netherlands

• Conforms to the European ISDN convention.
• If you have problems to call out using a KPN PRI, try with "dialplan=unknown" in the Zaptel PRI Trunk (previously OutgoingPRITrunk) interface

Denmark

Conforms to the European ISDN convention.

Germany

Germany uses an open dialplan which means that the number of digits in a number isn't fixed.

Example:

A client can have the following numbers:

• '24165007'
• '241650070'
• '2416500700'

This wouldn't necessarily be an issue, were it not for the fact that the number isn't sent in whole at once, but in parts. The digits '2416500' might arrive together, followed by '7' a bit later, followed by '0' a bit later.

2 solutions exist:

Only use numbers with a fixed length

This technique is preferred and advised by people with experience in the German telephony market.

Instead of keeping '24165007', '241650070', and '241650070', we only keep numbers in the format '24165007XX'. After the ISDN interface received the appropriate number of digits, the number is regarded as complete and sent on internally.

Waiting for a timeout

If the previous technique isn't an option, because numbers outside of the fixed length are publicized then waiting for a timeout is inevitable .

Example:

• Timeout is set to 3 seconds
• '2416500' is received
• 0,8 seconds later, '7' is received
• 1,1 seconds later, '0' is received
• No more digits are received for 3 seconds, regarding the number as complete, calling '241650070'

Ireland (Dublin)

If a complete number in Dublin were to be '14867800', only '7800' would be sent to the PBX. The number mapping should be modified to take this into consideration.

Switzerland

PRA's:

• EuroISDN
• CRC4: Yes
• TON CallerID: Unknown
• TON CalledID: Unknown
• Overlap dialing: Yes