Telephony Cards - How to Configure a Digium T1/E1 Card to Use E&M Signalling
Configuring a Digium T1/E1 Card (models TE12x, TE13x, TE2xx, TE4xx, TE82x) to use E&M signalling requires editing two files: /etc/dahdi/system.conf to configure DAHDI and /etc/asterisk/chan_dahdi.conf to configure Asterisk.
DAHDI Configuration
For T1 Lines:
Open (or create if it doesn't exist) the /etc/dahdi/system.conf file using your text editor of choice (vi, vim, nano)
Add the following sections, depending on how many spans your T1 card has:
Single span cards:
span=1,1,0,esf,b8zs
e&m=1-24
Dual span cards:
span=1,1,0,esf,b8zs
e&m=1-24
span=2,2,0,esf,b8zs
e&m=25-48
Quad span cards:
span=1,1,0,esf,b8zs
e&m=1-24
span=2,2,0,esf,b8zs
e&m=25-48
span=3,3,0,esf,b8zs
e&m=-26-72
span=4,4,0,esf,b8zs
e&m=73-96
Octal span cards:
span=1,1,0,esf,b8zs
e&m=1-24
span=2,2,0,esf,b8zs
e&m=25-48
span=3,3,0,esf,b8zs
e&m=-26-72
span=4,4,0,esf,b8zs
e&m=73-96
span=5,5,0,esf,b8zs
e&m=97-120
span=6,6,0,esf,b8zs
e&m=121-144
span=7,7,0,esf,b8zs
e&m=-145-168
span=8,8,0,esf,b8zs
e&m=167-192
Note: The Span option configures various timing, framing and encoding parameters. The first digit indicates which physical span (port) is being configured. The second digit indicates whether the span is receiving or providing timing: 1 configures the card to receive timing, 0 configures the card to provide timing. The third digit is the Line Build Out (LBO) distance: the distance from the telco drop to the span. ESF and B8ZS are the framing and encoding parameters for a standard T1 line.
To apply this configuration, either restart the dahdi service or run dahdi_cfg -vvv as root.
ForE1Lines:
Open (or create if it doesn't exist) the /etc/dahdi/system.conf file using your text editor of choice (vi, vim, nano)
Add the following sections, depending on how many spans your E1 card has:
Single span cards:
span=1,1,0,ccs,hdb3,crc4
e&m=1-31
Dual span cards:
span=1,1,0,ccs,hdb3,crc4
e&m=1-31
span=2,2,0,ccs,hdb3,crc4
e&m=32-62
Quad span cards:
span=1,1,0,ccs,hdb3,crc4
e&m=1-31
span=2,2,0,ccs,hdb3,crc4
e&m=32-62
span=3,3,0,ccs,hdb3,crc4
e&m=-63-93
span=4,4,0,ccs,hdb3,crc4
e&m=94-124
Octal span cards:
span=1,1,0,ccs,hdb3,crc4
e&m=1-31
span=2,2,0,ccs,hdb3,crc4
e&m=32-62
span=3,3,0,ccs,hdb3,crc4
e&m=-63-93
span=4,4,0,ccs,hdb3,crc4
e&m=94-124
span=5,5,0,ccs,hdb3,crc4
e&m=125-155
span=6,6,0,ccs,hdb3,crc4
e&m=156-186
span=7,7,0,ccs,hdb3,crc4
e&m=-187-217
span=8,8,0,ccs,hdb3,crc4
e&m=218-248
Note: The Span option configures various timing, framing and encoding parameters. The first digit indicates which physical span (port) is being configured. The second digit indicates whether the span is receiving or providing timing: 1 configures the card to receive timing, 0 configures the card to provide timing. The third digit is the Line Build Out (LBO) distance: the distance from the telco drop to the span. CCS and HDB3 are the framing and encoding parameters for a standard E1 line. CRC4 enables error checking on the line and is often standard for E1 digital connections.
To apply this configuration, either restart the dahdi service or run dahdi_cfg -vvv as root.
Asterisk Configuration
Configuring Asterisk to use the channels depends on several parameters. These parameters can be placed in the [channels] section of the /etc/asterisk/chan_dahdi.conf file, or in their own square-bracket defined section in the same file.
callerid: For T1/E1 lines, this should be set to asreceived.
context: The dialplan context, defined in extensions.conf, that the section is associated with.
signalling: If the span is configured in DAHDI to provide timing, this parameter should be set to em or em_w.
Configuration Sample For T1 Lines:
[T1-Config]
callerid=asreceived
context=incoming
signalling=em_w
Configuration Sample For E1 Lines:
[E1-Config]
callerid=asreceived
context=incoming
signalling=em_e1