Asterisk vs ISDN

Some information on how to conect Asterisk to the ISDN
Chapter 3-3:

Supported features

Last update:
<-- Chapter 3-2
NT-mode support
Chapter 4 -->
Conclusion / Contact


Choosing which way to go - Supported features

Now to the interesting bits...
Now that you use Asterisk, there is a vast amount of new features for you to explore. Many of them very advanced/sophisticated.
BUT: Many (if not most) of the more basic features you got used to in the last decade or two, may no longer work.
That includes rather fundamental PBX services like ECT (transfer). This is only supported with dahdi in the latest releases of all parts.
Support for HOLD and Call Waiting is also limited. And even dialling a number might not work the way you're used to.
The only thing that will always work is seeing who's calling. But the information might still not be as compete as you'd expect.
So here goes the unattractive part of what I found working and what not:
I have only investigated the options working with at least Asterisk 1.8 as that contains several changes to better support ISDN interworking and features.
That actually leaves five contenders: CAPI, dahdi, misdn1, misdn2/LCR and Sirrix.
I tried the svn version of chan_capi with an old kernel, remote capi and an FritzBox 7270 successfully. However it is not listed in the following table because the available features do not only depend on what chan_capi itself supports but also on what the CAPI you use for your hardware supports and on the other hand there doesn't seem to much active development, which sadly is true for most options by now.
Sirrix is not (yet?) listed as I just managed to make it work recently and I only have a PRI card by them which is not ideal for testing.

The table tells you what works beween terminals connected to Asterisk and between Asterisk connected to the Network, and where applicable in which direction(s).

Works with Asterisk 11 yes yes yes ¹² 1: use the git version
2: You need to manually add a #define ASTERISK_VERSION_NUM 110000 to the top of chan_lcr.c
Works with Asterisk 10 yes yes yes ¹ 1: use the git version
overlap dialling TE <> Ast <> net TE <> Ast <> net ¹ TE <> Ast <> net 1: No timeout on overlapping extensions
keypad TE  > Ast  > net ¹ unknown TE  > Ast  > net 1: Does not go to the dialplan
Depending on type of phone, this can make it impossible to dial any extensions starting with * or #

Seems to have been fixed somewhere in Asterisk 11
early media TE <  Ast <> net ¹ TE <  Ast <  net TE <  Ast <> net 1: Broken in Asterisk 1.8.4, fixed in 1.8.5
late media TE <  Ast <  net ¹ TE <  Ast <  net TE <  Ast <  net Tones/announcements after disconnect
1: Optional by delaying disconnect. WARNING:
Calls to applications like e.g. ConfBridge will never be released if enabled!
CLIP TE <> Ast <> net TE <> Ast <> net TE <> Ast <> net
CLIR TE <> Ast <> net TE    Ast    net TE <> Ast <> net
COLP TE <  Ast <> net TE <> Ast <> net TE    Ast    net ¹ 1: Works within LCR, not available to/from Asterisk
COLR TE <> Ast <> net TE <> Ast <> net TE    Ast    net
CALLERID(RDNIS) TE    Ast    net unknown TE <  Ast?net
REDIRECTING(from) unknown unknown TE <  Ast?net
REDIRECTING(to) unknown unknown TE    Ast    net
CW/HOLD TE  > Ast    net ¹ TE <  Ast    net ² TE <> Ast  > net ³ 1: only works if the channel is a bridged channel
2: Causes calls to be dropped sometimes
3: Fully supported in NT-mode including state display from Asterisk, Notify only in TE-mode
Also see note/conclusion in next chapter
3PTY / CONF TE    Ast    net TE    Ast    net TE    Ast    net ¹² Can only be done via dialplan
1: LCR offers its own conference feature, also accessible via dialling only
2: Native 3PTY support is curently being tested
ECT TE  > Ast    net TE    Ast    net TE  > Ast    net
Time/Date TE <  Ast    net TE <  Ast    net TE <  Ast    net
TP ("parking") TE    Ast    net TE    Ast    net TE  > Ast    net ¹ 1: Uses global IDs, not per interface; see note below
AOC TE <  Ast <> net ¹ TE    Ast    net TE <  Ast <  net ² 1: Needs aoc_enable in chan_dahdi.conf
2: Pass-through to other LCR channels only
CF TE    Ast    net TE    Ast    net TE    Ast    net CFU, CFB, CFNR, CFNA
CD TE    Ast  > net TE    Ast  > net TE    Ast    net
MSN / screening TE    Ast    net TE    Ast    net TE <> Ast <> net screening of supplied caller IDs and canonicalisation of numbers/types
CUG TE    Ast    net TE    Ast    net TE    Ast    net
SUB unknown unknown unknown
CCBS unknown ¹ TE    Ast?net TE    Ast    net 1: Is supposed to work between Asterisk and the Network (not yet tested)
CCNR unknown ¹ TE    Ast?net TE    Ast    net 1: Is supposed to work between Asterisk and the Network (not yet tested)
MWI unknown ¹ unknown TE    Ast    net 1: Should be available, but I have not found any information about it
UUS unknown unknown unknown
HLC/LLC TE    Ast    net unknown TE <> Ast <> net ¹ 1: Can be read and written within LCR, not available to/from Asterisk
G.722 TE    Ast    net TE    Ast    net TE    Ast    net Wideband CODEC
Alerting types TE    Ast    net TE    Ast    net TE    Ast    net Ringtone selection
NFAS TE <> Ast <> net TE    Ast    net TE    Ast    net Trunking of multiple interfaces with a common D-channel

Some additional information you should consider when trying to figure out what route to take:



<-- Chapter 3-2
NT-mode support
Chapter 4 -->
Conclusion / Contact