[Asterisk-Users] Detecting if a call is active on chan_sip before trying INVITE? (was Sip question - allow only 1 incoming call to sip phone)

[Kevin P. Fleming]

Roy Sigurd Karlsbakk wrote:

> Is it possible to test if a call to SIP/xxx is in place before dialling 
> out? This could help a lot to centralize administation of whether or not 
> to use call waiting instead of configuring the ATAs.

app_groupcount can be used to provide call counting in any fashion you 
desire.