T42G Pause in speed dial

[mcbsys]

I have a T42G running firmware 29.81.0.60.

I have added the following line to the provisioning file:

features.enhanced_dss_keys.enable = 1

On a 3CX phone system with 2-digit extensions, I want to check the voicemail of extension 11. So I set up a speed dial to dial 99, pause 1 second, then dial 11 and #:

99$Cp1$11#

When I press that speed dial, the entire string is passed to the VoIP provider. 3CX sends me this email:

"Call or Registration to 99$Cp1$11#@(Ln.10001@My SIP Account) has failed. "

I also tried this Speed Dial (with "wc" = wait connect), but had the same problem:

99$Cwc$11#

How do I insert a pause into a speed dial string?

Thank you,