Zaptel.conf:
loadzone = us
defaultzone=us
# ports for analog card
fxoks = 1-4

#ports and span definitions for T1 card
#note: span number is 2
span = 2,1,0,esf,b8zs
bchan = 25-34
dchan = 48

Result of ztcfg -vvv:
Zaptel Configuration
======================

SPAN 1: ESF/B8ZS Build-out: 0 db (CSU)/0-133 feet (DSX-1)

Channel map:

Channel 01: FXO Kewlstart (Default) (Slaves: 01)
Channel 02: FXO Kewlstart (Default) (Slaves: 02)
Channel 03: FXO Kewlstart (Default) (Slaves: 03)
Channel 04: FXO Kewlstart (Default) (Slaves: 04)
Channel 25: Clear channel (Default) (Slaves: 25)
Channel 26: Clear channel (Default) (Slaves: 26)
Channel 27: Clear channel (Default) (Slaves: 27)
Channel 28: Clear channel (Default) (Slaves: 28)
Channel 29: Clear channel (Default) (Slaves: 29)
Channel 30: Clear channel (Default) (Slaves: 30)
Channel 31: Clear channel (Default) (Slaves: 31)
Channel 32: Clear channel (Default) (Slaves: 32)
Channel 33: Clear channel (Default) (Slaves: 33)
Channel 34: Clear channel (Default) (Slaves: 34)
Channel 48: D-channel (Default) (Slaves: 48)

15 channels configured.



Zapata.conf:
[trunkgroups]

[channels] 
        context = default
        switchtype = national
        usecallerid = yes        
        echocancel = yes
        echocancelwhenbridged = yes
        ;add the is option if you are problems with DTMF detection
        relaxdtmf = yes 
        rxgain = 0.0
        txgain = 0.0
        signalling = fxo_ks
        group = 1
        channel => 1-4

[channels] 
         context = from-pstn
         switchtype = national
         usecallerid = yes        
         echocancel = yes
         echocancelwhenbridged = yes
         ;add the is option if you are problems with DTMF detection
         relaxdtmf = yes    
         rxgain = 0.0
         txgain = 0.0
         signalling = pri_cpe
         group = 1
         channel => 25-34