ATM there is no snandalone rpm package for iLBC in Fedora but it seems to be changed very soon.
sems-1.4.3-4.fc17 has been submitted as an update for Fedora 17. https://admin.fedoraproject.org/updates/sems-1.4.3-4.fc17
sems-1.4.3-4.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/sems-1.4.3-4.fc18
sems-1.4.3-4.el6 has been submitted as an update for Fedora EPEL 6. https://admin.fedoraproject.org/updates/sems-1.4.3-4.el6
Package sems-1.4.3-4.el6: * should fix your issue, * was pushed to the Fedora EPEL 6 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=epel-testing sems-1.4.3-4.el6' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-EPEL-2012-13518/sems-1.4.3-4.el6 then log in and leave karma (feedback).
sems-1.4.3-4.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.
sems-1.4.3-4.fc17 has been pushed to the Fedora 17 stable repository. If problems still persist, please make note of it in this bug report.
sems-1.4.3-4.el6 has been pushed to the Fedora EPEL 6 stable repository. If problems still persist, please make note of it in this bug report.