I'm working on my first real Cisco router as a gateway for voice calls. Based on advice I received from a Cisco reseller and other info I've seen online, this is how my config ended up. The router has a 4 port T1/E1 card. We have 4 live ISDN PRI circuits in use. The router is setup as a SIP Trunk on CUCM (10.5.2).
One thing I noticed with my initial config is that the calls were scratchy and rather poor quality. I had the encapsulation set to PPP at that point. So I changed it to HDLC and the quality of the calls was excellent. No noise and overall good quality. Is there any ryhme or reason as to why you'd use PPP vs. HLDC and vice versa in the US when connecting to common telcos like AT&T and Verizon? (assuming ISDN PRI with National ISDN 2 (NI2) as the protocol).
Can you see anything I'm missing in my basic config for this type of setup? I didn't paste in the dial-peers below because I'm mainly just interested in the config of the T1 itself (controller) and the D channel (serial interface).
The reason for the isdn map address ^011 plan unknown type unknown entry is so that I can mark 011 calls as unknown and send 011 to the telco for international calls.
I appreciate your input! Thanks...
card type t1 0 0
network-clock-participate wic 0
network-clock-select 1 T1 0/0/0
network-clock-select 2 T1 0/0/1
network-clock-select 3 T1 0/0/2
network-clock-select 4 T1 0/0/3
isdn switch-type primary-ni
controller T1 0/0/0
description ATT-ISDN-PRI-1
framing ESF
linecode B8ZS
pri-group timeslots 1-24
controller T1 0/0/1
description ATT-ISDN-PRI-2
framing ESF
linecode B8ZS
pri-group timeslots 1-24
controller T1 0/0/2
description ATT-ISDN-PRI-3
framing ESF
linecode B8ZS
pri-group timeslots 1-24
controller T1 0/0/3
description ATT-ISDN-PRI-4
framing ESF
linecode B8ZS
pri-group timeslots 1-24
interface Serial0/0/0:23
no ip address
encapsulation hdlc
isdn switch-type primary-ni
isdn incoming-voice voice
isdn map address ^011 plan unknown type unknown
isdn supp-service name calling
no cdp
interface Serial0/0/1:23
no ip address
encapsulation hdlc
isdn switch-type primary-ni
isdn incoming-voice voice
isdn map address ^011 plan unknown type unknown
isdn supp-service name calling
no cdp
interface Serial0/0/2:23
no ip address
encapsulation hdlc
isdn switch-type primary-ni
isdn incoming-voice voice
isdn map address ^011 plan unknown type unknown
isdn supp-service name calling
no cdp
interface Serial0/0/3:23
no ip address
encapsulation hdlc
isdn switch-type primary-ni
isdn incoming-voice voice
isdn map address ^011 plan unknown type unknown
isdn supp-service name calling
no cdp
trunk group ATT-LOCAL-ISDN-PRI
controller t1 0/0/0
trunk-group ATT-LOCAL-ISDN-PRI timeslots 1-24 preference 1
controller t1 0/0/1
trunk-group ATT-LOCAL-ISDN-PRI timeslots 1-24 preference 2
controller t1 0/0/2
trunk-group ATT-LOCAL-ISDN-PRI timeslots 1-24 preference 3
controller t1 0/0/3
trunk-group ATT-LOCAL-ISDN-PRI timeslots 1-24 preference 4
