syntax is as folows:

span=<"spannum">,<"timing">,<"LBO">,<"framing">,<"coding">

Before going any further, lets have a closer look at these options:

spannum:

This defines the number of the span (=port). This is counted across the cards. (have a look at the picture of the te4xxp cards to see where it starts counting.

E.g.:

If you have a quad e1/t1 card, and a single port e1/t1 card, you will need 5 spans.

Span 1 might be on the first card or on the second card, so there are two options:

span 1 = first port on the single port card.
span 2,3,4,5 = the ports on the quad port card.

or span 1,2,3,4 = the ports on the quad port card
span 5 = the first port on the single port card.

LBO= Line Build Out – Length of cable between Zap card and SmartJack/telco provided modem. Almost always should be set to 0 unless you have a long cable. This distance does NOT include the copper in the street to the CO/exchange.
0: 0 dB (CSU) / 0 – 133 feet (DSX-1)
1: 133 – 266 feet (DSX-1)
2: 266 – 399 feet (DSX-1)
3: 399 – 533 feet (DSX-1)
4: 533 – 655 feet (DSX-1)
5: -7.5 dB (CSU)
6: -15 dB (CSU)
7: -22.5 dB (CSU)

Framing and coding:

Lets have a look at the possible options for a T1 setup:

- Framing: how to communicate with the hardware at the other end of the line.
D4 or ESF

- Coding:another parameter of the communication with the other end of line hardware.
AMI or B8ZS

Usually when the line is ESF framing, the line coding is B8ZS and when the line is D4 SF framing, the line coding is usually AMI.

e.g.: span=1,1,0,esf,b8zs

Lets have a look at the possible options for an E1 setup:

- Framing:
CCS or CAS

- Coding:
AMI or HDB3

On an E1 card, you can optionally enable CRC checking.

e.g : span=1,1,0,CCS,HDB3,crc

Timing:

As mentioned before, every line needs to have a synching time source on one of both ends. (An asterisk PRI line can be clocked internally or can be clocked by the telco or the PBX it is connected to.)

Lets rephrase this to make this a little more clear:

Internal timing is when the timing is taken from the clock in the card.
External timing is when the timing is taken from the line on the PRI.

Timing is done PER card, so every card needs its own timing sources defined. (they can NOT be shared across cards.)

The timing parameter in the span definition in zaptel.conf determines the selection of primary, secondary, and so on sync sources. If the span you are defining should be considered a primary sync source, then give it a value of “1″.
(This means, zaptel will take the timing as received on the line connected to this port (span). This is called external clocking. if no timing was received on this line, it will fallback to internal clocking, meaning it will look at its own clock chip and generate timing,)

To define a secondary clock source, use “2″, to define a 3rd one, use 3, and so on.

span=1,1,0,esf,b8zs – This is the FIRST digital Zaptel span on the system, has PRIMARY priority to receive timing FROM the other end of the link, the cable to the SmartJack/modem is less than 133 feet in length, this span uses ESF framing and B8ZS line encoding. A fairly typical T1 span definition.

span=2,2,0,ccs,hdb3,crc4 – This is the SECOND digital Zaptel span on the system, has SECONDARY priority to receive timing FROM the other end of the link, the cable to the SmartJack/modem is less than 133 feet in length, this span uses CCS framing and HDB3 line encoding, CRC4 error checking is also enabled. This is a fairly typical second E1 span definition.

A sample configuration for the zaptel.conf file having 2 spans in the E1 card

span=1,1,0,ccs,hdb3
bchan=1-15,17-31
dchan=16
loadzone = in
defaultzone= in
span=2,1,0,ccs,hdb3
bchan=32-46,48-62
dchan=47

Tags: Asterisk, Zaptel, zaptel configuration, zaptel configuration asterisk, zaptel.conf