Not sure who you are trying to reach by phone. The Splunkbase community has people from Splunk proper, as well as customers and partners. Are you trying to reach Splunk support or the owner of a particular app? For Enterprise Splunk Support can be reached by submitting a support case at https://www.splunk.com/page/submit_issue. If it's an app owner you are trying to reach, then it's unlikely that you'll be able to contact them by phone.
You might have some luck with the Splunk IRC channel -- join #splunk on EFNet.