Consultancy
AgileCO.net - AgileCO.net offers Advanced Integration and Develpment for OpenSER; SIP; Skype; ViaSIP; 3GP; IMS; Mobicents; ParlaX and XML WebServices SOAi OSS/BSS. Operate in Europe; Asia and Americas.
Asipto - SIP/VoIP consultancy; training and development for OPENSER SIP server
Baraap Technologies - Custom SIP integration technical services using the Java platform (JAIN).
BLUEdev LTD - We provide complete VoIP solutions using SIP to the Greek SOHO market. We offer solutions using Asterisk and SER; but also server-less or totally wireless solutions to minimize cost and infrastructure
Datatend Ltd - Hosted telephony platforms delivered to telco, ISP and ITSP using SIP based technologies including Broadsoft and Kagoor. End to end solutions, UK based.
Drishti Soft Solutions - Open Source/Proprietary Services for SIP and related VoIP Technologies.
FACTSplus - Intl Convergence Consultancy, Design, and Project Implementation & Management for SIP based VoIP platforms and CPE as well as Asterisk and open telephony services. Apple ran shop.
HCL Technologies - SIP specific application development; porting; integration ; testing consultancy services
Mannaz Consulting - Areas of specific expertise include voice over IP, softswitch, and bypassing the PSTN.
Napa Consulting Group - Leader in SIP Management consulting and marketing firm.
Nearshoring2Canada - We offer Asterisk PBX; SIP and Linux related consultancy services. Our consultancy includes Contact Center; Audio Conferencing; Customer Premise Do Not Call Blockers; PBX; IVR and Voice Recording s/w
Peninsula Communications - Provides sales, installation and support of Zultys Technologies complete line of IP products. We also provide security soultions for Voip enabled networks.
Purple Packet - internationally recognised consultants with specialist strategic knowledge of emerging communications technologies and markets especially those centred around VoIP (Voice over Internet Protocol) and SIP (Session Initiation Protocol).
Software Invent - Whether it's medical imaging, telecommunications, clinical speech or internet lead trading, Software Invent provides consistent results in a variety of markets.
vCERT - VoIP Certification, VoIP Training, Consulting, Interoperability testing, Product Manager's Guide.
Voice Sistem - Design, consultancy and technical support for SIP Express Router (SER) based VoIP platforms
VOiCOM - Convergence Training and Consultancy Services
Employment Services
See also: SIP Center careers page
cs.columbia.edu - Opportunities for VoIP/SIP Interns and Other SIP-Related Job Opportunities
Pulver.com/jobs
NetworkWorldFusion Jobs search
Total Telecom Recruitment
careers.telecoms.com
Nicholson International
Training
See also: SIP Training Courses
The SIP School - 
- Backed by industry players such as Mitel and Panasonic, The SIP School is the premier SIP Training site for VoIP professionals needing to get trained on this important protocol. To see what is on offer please have a look at our DEMO and note that for an access license you will get full access to the SIP Training course and the chance to take the SSCA test to get yourself certified on this emerging accreditation program.
SIPKnowledge 
eLearning courses and self training on SIP, IP Telephony and 3G IMS.
FUTURENETZ SIP Courses focused on IP Multimedia Services in 3G Networks.
Apis Technical Training - Leading provider of instructor-led; high quality training in IMS; SIP; and IP for Mobile Networks. We offer training globally.
Cameron Communications Group - "Mastering the Session Initiation Protocol" eLearning Course lets the learner progressively drill down into greater levels of complexity until complete mastery of SIP is achieved. $50 discount for SIP Center visitors - Promotion code 21f20e4451b6.
goVoIP.com
IP-Solutions - Training within: VoIP with SIP, SIP advanced, IMS Overview, IMS technical, IMS security, IP-TV, MobileTV etc. Many practical exercises and experienced trainers.
LEVER Technology Group has the strongest portfolio of Wireless, Telecommunications, IP Networks and Mobile Communication education tracks in Europe. Call 0800 138 3030for schedule.
mpirical limited - SIP Training, IMS Training, SIP IMS Courses
MyVoipProvider - Review; comparison and ranking of international SIP / VoIP services. Growing VoIP directory with almost 600 VoIP phone providers
Network Intelligence - Managed Network Access for SIP Termination/Origination. Network Intelligence has evolved from providing our clients with information and advice to providing fully customized & outsourced operations.
Oasis Knowledge - SIP Training - SIP Business is a one day SIP Seminar for non technical executives. SIP Tech is a two day workshop created for technical staff.
Ossidian Technologies - SIP Fundamentals eLearning provides a comprehensive overview of the protocol; its applications; and related systems. Details the basic principles; architecture; message-format; structure and process.
Perpetual Solutions provides corporate training solutions on SIP, SIP-T, SIP-I as well as a complete range of Next Generation Network Training.
PTT - PTT's interactive e-learning course "Advanced IP networks" which discusses the delivery of SIP and H.323-based telephony over IP networks, is available on CDROM or online.
SIP For Engineers - Systems & Network Training provide hands on technical instructor led training courses in networking and telecommunications including courses such as our three day VoIP, 2 day SIP and 3 day Asterisk course.
SIPFUN.NET - The Free SIP Directory: An independent listing (white pages) over SIP users around the world.
Techtionary - QoS & CoS in a VoIP Network – Special Course Lesson - This information was developed for a lesson in the BCR onsite course and the NACSE online course called Channel Provider & Partner Strategies for VoIP course written by the course instructor Thomas B. Cross.
Technology Training Limited - SIP; IMS and VoIP training courses and consultancy through UK public courses and on-site courses worldwide. Also covering 3GPP; TISPAN; H.248; SIP Security and SIP Devices
Telecoms Academy
Turn2VoIP - VoIP news and special features including SIP hardware providers and SIP VoIP providers. Good starting base for Knowledge on SIP and VoIP technology.
vCERT - VoIP Certification, VoIP Training, Consulting, Interoperability testing, Product Manager's Guide.
VOiCOM - Convergence Training and Consultancy Services
VoIP Corp - VoIP Corporation is a world class communication company; owns and operates one of the largest IP networks in the world. Wholesale Services: SIP Peering; DID Origination; A to Z Termination; E-91
Vonage - Vonage provide VoIP adapters; IP phones and other SIP supported VoIP equipment both for business and residential customers. Also offering cheap national and international calls in the UK using VoIP.