You can't just dial SIP with an IP address only - that's not a valid SIP format. It must be an alias@domain or alias@ipaddress (ie alias@10.10.10.10) format.
In your example above, you should be able to dial "std322.10@10.88.17.5" or "std322.11@10.88.17.55" - both of these are valid SIP addresses. The straight IP address 10.88.17.5 is not.
PS - As mentioned by Patrick, you really should upgrade your software on your endpoints to a newer version. There's a Security Advisory that should assist you getting the new software, even without an active service contract: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140605-openssl
Wayne
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Wayne
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