Ok, you are still using the first Issabel iso. the new one they change all repo.
Look this is my version
Kernel
Linux(x86_64)-3.10.0-514.2.2.el7.x86_64
Issabel
issabel-4.0.0-1
issabel-addons-4.0.0-1
issabel-agenda-4.0.0-1
issabel-asterisk-sounds-1.2.3-1
issabel-callcenter-4.0.0-1
issabel-email_admin-4.0.0-1
issabel-endpointconfig2-4.0.0-1
issabel-extras-4.0.0-1
issabel-fax-4.0.0-1
issabel-firstboot-4.0.0-1
issabel-framework-4.0.0-1
issabel-my_extension-4.0.0-1
issabel-pbx-4.0.0-1
issabel-portknock-4.0.0-1
issabel-reports-4.0.0-1
issabel-security-4.0.0-1
issabel-system-4.0.0-1
RoundCubeMail
RoundCubeMail-0.3.1-12
Mail
postfix-2.10.1-6.el7
cyrus-imapd-2.4.17-8.el7_1
IM
openfire-(not installed)-
IssablPBX
issabelPBX-2.11.0-43
Asterisk
asterisk-11.25.0-0.el7.centos
asterisk-perl-1.03-0
asterisk-addons-11.25.0-0.el7.centos
FAX
hylafax-4.3.11-1rh7
iaxmodem-1.3.0-0.el7.centos
DRIVERS
dahdi-2.10.2-0.el7.centos
rhino-0.99.7-0
wanpipe-util-7.0.14.3-0
Also on Centos 7 i had some Network issues that in the new one they fixed.
Also I recomend to download and try the new one so you can run yum update to your system.
Regards
David C.