Hi Hoanghiep,

You have two options, one being more straight forward than the other to implement, this depends on your requirements.

Firstly you can configured both phones with the same DN, thus making them a shared line appearance. For example if you configured DN 1234 on both phones then when you dial 1234 both Phones will ring simultaneously.

The second option is applicable if you require both phones to have unique DNs that ring at the same time. If this is the case then you can configure these Phones as members of a broadcast line-group.

A line group allows you to designate the order in which directory numbers are chosen. Cisco Unified CallManager distributes a call to idle or available members of a line group based on a call distribution algorithm and on the Ring No Answer Reversion (RNAR) Timeout setting.

There are three steps for configuring this method:-

1. Configure the Line-Group and associate members/extensions.

2. Configure the Hunt-List and associate the Line-group in step 1 with this list.

3. Configure the Hunt-Pilot which is the specific number to call in order to route the call the line-group members. Here you associate the hunt-list in step 2.

Look at the folloing links for configuring the above:-

1.Line-Groups

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00808b41d4.html

2.Hunt-List

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00808b41d1.html

3.Hunt-Pilot

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00808b41d3.html

Hope this helps.

Regards

Allan.