You can use Voicent software with Vonage directly (You do not need voice modem and the Vonage router/ATA box). Calls can be directly routed from Voicent software to the Vonage VOIP (SIP) service. The bad news is that, unlike other VOIP services, you must pay extra (have Vonage Softphone feature for your Vonage service) in order to use its SIP service without the ATA box. Standard Vonage service is locked to the router/ATA they send you. It is not possible to connect to it through SIP.
Vonage sells an addon service called Vonage Softphone. Some Vonage business plans may include the softphone feature. Once you have this feature, you can use Voicent software with Vonage without a voice modem and the Vonage router/ATA box.
If your call volume is high, you may need to get a Vonage plan that is for business. All “unlimited” calling plans for residential account have usage limit.
Configure Voicent to use Vonage
Starting from release 8.3.0, you can simply follow the phone setup wizard to configure Voicent for Vonage. Open Voicent Gateway, select Setup > Phone Setup Wizard. Follow the onscreen instructions to complete the setup.
For earlier releases or if you want to configure it manually, follow the instruction below.
Suppose your Vonage phone number is 1-408-123-4567, you can use the following SIP credentials to configure Voicent. Open Voicent Gateway, select Setup > Options > SIP tab. Enter the following:
SIP ID: 14081234567
Domain: sphone.vopr.vonage.net
User: 14081234567
Password: ****
Use any text in the Display Field.
1. Please remember to use your own vonage phone number instead of 14081234567
2. The password is not your regular Vonage account password. It is listed under the softphone feature page.
Log on to your Vonage Online Account, click the Features tab, click Manage SoftPhone Lines. Your SoftPhone account number and Password are displayed on this page. You will be required to enter the SoftPhone Account Number and Password exactly as they appear on the page.
Other settings
Stun Server: stun.xten.com (default port)
Codec: PCMU