Phone interviews are often the first interview you have with an employer. It is usually a "screening" interview to see if you sound like a good person to consider interviewing in person. If you pass this hurdle, your candidacy will move forward and the employer will continue with their vetting process to see if you should be hired.
As with all other aspects of job interviewing, how you handle your phone interview is very important as an indication of the quality of your work (and is, thus, another important hurdle to successfuly overcome). Your thank you helps the employer determine some important things:
As usual, an emailed thank you is acceptable by the vast majority of employers. In fact, these days a hand-written and snail-mailed thank yous may be received several days later, labeling you as old-fashioned and not quick to respond, even if mailed immediately after the interview. This delay may cost you the opportunity.
[Related: 12 Tips for Telephone Interviews Success]
As ususal, leave the TO: field empty until you have completed, spellchecked, and proofread the message (or put your own address in that field until it is ready to be sent).
Send a formal business message.
Don't try to be cute or funny. No emoticons :-( and no texting language (LOL).
[More: Guide to Email for Job Search.]
Replace the Italicized text with whatever terms are appropriate for you and your situation.
Subject: [Job Title] interview on [date]
Dear [Mr./Ms. Last Name]:
Thank you very much for your time today [or yesterday or the date] to discuss the position of [job title]. I appreciate the opportunity to learn more about this job, and I look forward to discussing this position in person [on date and time, if the in-person interview was scheduled].
[Reference anything you said that seemed important to the interviewer, like: As we discussed, I find the technology related to using cloud computing fascinating and an amazing opportunity for the future, but security is also a major concern. Keeping XYZ Company's information safe would be a top priority for the person in this job, and I would love to dig deeply into the protective technologies, as well as the threats, to avoid future problems.]
As we discussed, I have [months or years] of experience with [technology, tools, or qualification you have that seemed most important in the interview]. With my background and experience, I believe that I could become a contributor very quickly, and I would love to meet your team and learn more about this opportunity.
I am excited about this opportunity at [organization name], and I look forward to hearing from you [whenever they said they would be in touch or "soon" if they didn't specify a date] to meet you in person.
[ Your job title or tagline, like "eCommerce Customer Support Specialist"]
[LinkedIn Profile URL]
[Phone number -- not your work number if you are employed]
If you are employed, do NOT send this message from your work email, your work computer, your work smartphone, or while you are in the office! Your employer may discover the message and your intentions to leave. The result is that you could have a very uncomfortable discussion with your boss about your job search, or you could lose your job. So, send this message from home using your own personal computer and your personal (not work!) email account.
Hopefully, you asked at the end of the interview if email is an acceptable form of communicating about this job.
Studies have shown that emailed thank you's are acceptable to most employers. However, I urge caution if the organization is very formal or "old school" like some old-line law firms, consulting companies, universities, and other similar "traditional" organizations.
More information: Sending Your Thank You After the Job Interview
Online job search expert Susan P. Joyce has been observing the online job search world and teaching online job search skills since 1995. A veteran of the United States Marine Corps and a recent Visiting Scholar at the MIT Sloan School of Management, Susan is a two-time layoff “graduate” who has worked in human resources at Harvard University and in a compensation consulting firm. Since 1998, Susan has been editor and publisher of Job-Hunt.org. Follow Susan on Twitter at @jobhuntorg and on Facebook, LinkedIn, and Google+.