Zoho CRM - Omnichannel CRM for Businesses of all sizes
Postscript - Like Mailchimp for SMS
Pipedrive - Sales pipeline software that gets you organized. Helps you focus on the right deals, so easy to use that salespeople just love it. Great for small teams.
Tatango - Tatango is a mobile messaging platform for agencies.
Copper - Copper (formerly ProsperWorks) is easy-to-use customer relationship management for small businesses. Capture contacts and sales leads direct from Gmail with our simple CRM.
Flowroute - Flowroute provides direct access to telephony resources - such as calling, messaging (SMS & MMS), call routing, SIP Trunking and Communication APIs.