asterisk users - Nov 2005 - Comas versus pipe command in AgetCallBackLogin

H,

Not sure if this is normal but I thought the coma ',' was replaceable by
the
pipe command '|' and vice versa? When I used comas instead of the pipe
command
in AgentCallbackLogin certain SIP phones do not here the operator prompts when
calling the agent extension. Is this normal - I thought the pipe command and
coma were interchangeable??? Oh and I am using Asterisk 1.2.

Works:

exten => 801,1,AgentCallbackLogin(||@extensions-home)

Does not work:

exten => 801,1,AgentCallbackLogin(,,@extensions-home)

Thanks