Which dial-peer configuration routes calls from SIP-based phones on Cisco Unified Communications Manager Express to Cisco Unity Express?

A.
```
dial-peer voice 7000 voip
destination-pattern 7000
session protocol sipv2
session target ipv4: codec g711alaw
```

B.
```
dial-peer voice 7000 voip
destination-pattern 7000
session protocol sipv2
session target ipv4: codec illc
```

C.
```
dial-peer voice 7000 voip
destination-pattern 7000
session protocol sipv2
session target ipv codec g711ulaw
```

D.
```
dial-peer voice 7000 voip
destination-pattern 7000
session protocol sipv2
session target ipv4: codec 972916
```

A correct dial-peer configuration in Cisco Unified Communications Manager Express routes calls from SIP-based phones to Cisco Unity Express, option b is correct.

Explanation:

Dial-peer configuration in Cisco Unified Communications Manager Express routes calls from SIP-based phones to Cisco Unity Express. Option B is the correct configuration to achieve this, as it specifies the necessary settings for the routing to take place successfully.

This configuration defines a VoIP dial-peer (voice 7000) for SIP-based phones, with a destination pattern matching calls intended for Cisco Unity Express (7000). It specifies the session protocol as sipv2 and designates the target IPv4 address of Cisco Unity Express.

Additionally, it sets the codec to g711alaw, ensuring compatibility and optimal voice quality during call routing between the two systems. This setup facilitates seamless communication between SIP-based phones on Cisco Unified Communications Manager Express and Cisco Unity Express voicemail services.