SIP Trunk to SPA3102 - predial delay through a KSU

I using FreePBX / Asterisk with a SPA3102 behind an existing ESI IVX KSU. From the IVX, line group 9 gets an outside line. I have a trunk connected through to SPA3102 PSTN Line. Extension to extension calls between the two systems work fine as expected. For making an outside call from Asterisk I’ve tried setting up the trunk with the Outbound dial prefix. I’ve tried putting in the string 9wwww so I get a wait after the 9. I see in the verbose debug that the Dial app sip trunk line includes the 9wwww prefixed to the outside number. However the delay never seems to be implemented and the early digits are eaten. I’ve also tried adding the 'P1 ’ to the dialplan of the SPA3102 PSTN dialplan entry but that doesn’t seem to have any effect either.

I found a couple articles that are similar to my problem but they seem to address issues with calling cards / pins and long distance service code access.

Any suggestions on how I can implement the delay in this configuration and why what I’ve tried doesn’t work?

I finally managed to figure out how to configure the SPA3102 to add the delay. The admin guide I’m using from Cisco indicates the P parameter for pause is in seconds. However on mine it seems to much smaller. For my PSTN my dial plan 1 looks like this:

Dial Plan 1 : ([1-3]xx|<9:9P6 >[2-9]xxxxxx|<9:9P6 >911)

This gives me just under a 2 second delay from what I can tell. It is enough that it seems to work reliable at giving me the delay needed.

Attempting to use the FreePBX trunk predial mechanism doesn’t seem to have any way of supporting this with the SPA3102 as I gave up on trying to do that. Seems the solution with the dial plan is better anyway as it lets me use the trunk for more than one purpose.