Need help configuring a serial T1 connection in between 2 routers for voip traffic

[NetEng20k]

Hello!

Im new to voip. I'm taking an online ccna voice course. Im labbing this all up using real equipment. Everything is going great so far however, I've reached a stumbling block. In the lab there is voice traffic that's going from one router to another. One router is running CME while the other has 2 simple POTS dial peers for 2 analog phones using FXS ports, which are working and can call each other. The CME router has 4-5 functional IP phones and 1 CIPC, all can call each other.

My problem is in between the 2 routers. The voice traffic is not crossing over. They are connected to each other using VWIC3s as serial interfaces with a T1 crossover cable. The interfaces have green LEDs and they can ping each other.

Below is a look at the router to router topology:

This is what I configured for the Legacy router:

LEGACY_VOICE_NJ#conf t

#card type t1 0

#controller t1 0/1/0

#linecode b8zs

#framing esf

#channel-group 0 timeslots 1 - 24

#exit

#int Serial0/1/0:0

#ip add 10.1.1.2 255.255.255.0

#no shut

#end

This is what I configured for the CME router:

CME_VOICE_NY#conf t

#card type t1 0

#controller t1 0/1/0

#linecode b8zs

#framing esf

#channel-group 0 timeslots 1 - 24

#exit

#int Serial0/0/0:0

#ip add 10.1.1.1 255.255.255.0

#no shut

#end

This is the voip dial peer config on the CME router pointing to the 3301 and 3302 extensions in the legacy router:

CME_Voice_NY(config)#dial-peer voice 330 voip
CME_Voice_NY(config-dial-peer)#destination-pattern 330.
CME_Voice_NY(config-dial-peer)#session target ipv4:10.1.1.2
CME_Voice_NY(config-dial-peer)#end

Because the CME voip lan is in the 172.16.1.0/24 subnet and unknown to the legacy router, i setup eigrp in between them to which the legacy router knows about the advertisement and can ping it. The issue is with the calls, they won't go across the routers. Can anyone help or at least lead me in the right direction? Yes, I've researched it and have tried several different things but no dice.

[Elliot Dierksen]

How are you exchanging routes between the two routers? I suspect you are not. What does a "show ip route" look like on each router? You can either set up routing protocols between the two of them, or do static routes if they don't know about each others networks.

[NetEng20k]

Hi Elliot, thank you for responding!

At the moment, the CME router is advertising its 172.16.1.x lan to the Legacy Voice router using EIGRP. The legacy router has learned the route and can ping inside the 172 subnet. The Legacy router only has the 10.1.1.0/24 subnet  which is directly connected to the CME router. Here is the sh ip route output from both anyway:

Legacy Router

LEGACY_VOICE_NJ#sh ip ro
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.0/24 is directly connected, Serial0/1/0:0
L 10.1.1.2/32 is directly connected, Serial0/1/0:0
172.16.0.0/24 is subnetted, 1 subnets
D 172.16.1.0 [90/2178816] via 10.1.1.1, 02:46:21, Serial0/1/0:0

CME Router

CME_Voice_NY#sh ip ro
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
+ - replicated route, % - next hop override

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.0/24 is directly connected, Serial0/0/0:0
L 10.1.1.1/32 is directly connected, Serial0/0/0:0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
C 172.16.1.0/24 is directly connected, GigabitEthernet0/0.10
L 172.16.1.1/32 is directly connected, GigabitEthernet0/0.10
C 172.16.2.0/24 is directly connected, GigabitEthernet0/0.50
L 172.16.2.1/32 is directly connected, GigabitEthernet0/0.50

[NetEng20k]

Here are the eigrp configs for each:

Legacy

LEGACY_VOICE_NJ#sh run | s eigrp
router eigrp 1000
network 10.1.1.0 0.0.0.255

CME

CME_Voice_NY#sh run | s eigrp
router eigrp 1000
network 10.1.1.0 0.0.0.255
network 172.16.1.0 0.0.0.255

They can ping each other. Legacy can get to the internal 172 subnet of the CME router. There is no other subnet configured under the Legacy router. The phones are on 2 FXS ports.

[Elliot Dierksen]

Are you trying to use H.323 or SIP for the VoIP legs? What dial peers do you have on the FXO/FXS side?

[NetEng20k]

Honestly, Im not sure about H.323 or SIP, thats what the lab video leaves out. These are the dial peers for the FXS ports:

LEGACY_VOICE_NJ#sh run | s dial-peer
dial-peer voice 3301 pots
destination-pattern 3301
port 0/0/0
dial-peer voice 3302 pots
destination-pattern 3302
port 0/0/1

[Elliot Dierksen]

You need a VoIP dial peer that references the calling router, or you need to add it to the trusted IP address list in "voice service voip"

[NetEng20k]

Not sure what that means exactly, but this is what I have for voip service voip on the CME router:

!
voice service voip
allow-connections h323 to sip
allow-connections sip to h323
allow-connections sip to sip
fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none
sip
registrar server expires max 600 min 60
!

What does that voip service voip config mean?

[Elliot Dierksen · Accepted solution]

The receiving router (one with the FXO/FXS ports) isn't accepting the call because it doesn't trust the IP of the calling router. Add the statements below to make it trust the serial IP of the calling router. voice service voip ip address trusted list ipv4 10.1.1.1

[NetEng20k]

Thank you Elliot!! This worked!!! Question, is there a debug or perhaps a show command that I could run on either router that would tell or help me identify this as the issue?
Side note.. I cant see my post anymore so Im responding over email.
Thanks again man!! Im finally able to continue on with the class and lab.

[Elliot Dierksen]

My goto debug is "debug voip ccapi inout". It generates a TON of output, but it will almost always help point you in the right direction.