It’s absolutely the same for all Linksys/Sipura SPA/PAP2 products.
This is my example for PAP2:
[11]
; pap2 line2
fullname = Master
email =
secret = password
cid_number = 11
context = longdistance
hasvoicemail = yes
vmsecret = 1111
hassip = yes
hasiax = no
host = dynamic
dtmfmode = rfc2833
disallow = all
allow = alaw
allow = ulaw
allow = g729
t38pt_udptl = no
On SPA you will need to enter your User ID (11 in my case) and Password as well as Proxy (your server name or ip address) - on Line1/Line2 page. The most of other settings you may leave by default. Just try 
Make sure you upgraded the software on SPA.